Construction machine control system, construction machine, and method of controlling construction machine

ABSTRACT

A method of controlling a construction machine including a work machine including a boom, an arm, and a bucket, the method comprising: determining a speed limit according to a distance between the bucket and a target excavation landform based on the target excavation landform and bucket position data and limiting a speed of the boom so that a speed at which the work machine approaches the target excavation landform is equal to or smaller than the speed limit; operating an operating device in order to drive a movable member including at least one of the arm and the bucket; detecting an amount of operation of the operating device; setting a limited amount of operation for limiting a speed of the movable member based on a detection result of the detection device; and outputting a control signal so that the movable member is driven with the limited amount of operation.

FIELD

The present invention relates to a construction machine control system, a construction machine, and a method of controlling construction machine.

BACKGROUND

A construction machine like an excavator includes a work machine that includes a boom, an arm, and a bucket. As a method of controlling a construction machine, Patent Literatures 1 and 2 disclose limited excavation control in which a bucket is moved based on a target excavation landform indicating a target shape of an excavation object.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent Application Laid-open No. 2013-217138

Patent Literature 2: Japanese Patent Application Laid-open No. 2006-265954

SUMMARY Technical Problem

A construction machine includes an operating device that an operator operates to drive a work machine. In the limited excavation control, if a boom is not moved at a high speed but is slower than an arm and a bucket, the bucket may not be moved based on a target excavation landform and excavation accuracy may decrease.

An object of some aspects of the present invention is to provide a construction machine control system, a construction machine, and a method of controlling the construction machine capable of suppressing a decrease in excavation accuracy.

Solution to Problem

A first aspect of the present invention provides a construction machine control system that includes a work machine including a boom, an arm, and a bucket, the system comprising: a boom limiting unit that determines a speed limit according to a distance between the bucket and a target excavation landform indicating a target shape of an excavation object based on the target excavation landform and bucket position data indicating the position of the bucket and limits the speed of the boom so that a speed at which the work machine approaches the target excavation landform is equal to or smaller than the speed limit; an operating device that is operated in order to drive a movable member including at least one of the arm and the bucket; a detection device that detects an amount of operation of the operating device; and a movable member control unit that outputs a control signal so that the movable member is driven with a limited amount of operation for limiting a speed of the movable member based on a detection result of the detection device.

In the first aspect of the present invention, it is preferable that the construction machine control system, further comprises: a timer that starts time measurement based on the detection result of the detection device; and a limit value setting unit that sets the limited amount of operation for limiting the speed of the movable member in association with time elapsed from a start time of the time measurement of the timer, wherein the movable member control unit outputs a control signal so that the movable member is driven with the limited amount of operation in a predetermined period from the start time of the time measurement of the timer.

In the first aspect of the present invention, it is preferable that the start time of the time measurement of the timer includes at least one of a start time of an operation of the operating device, time at which a detection value of the detection device exceeds a threshold value, and time at which an amount of increase per unit time of the detection value of the detection device exceeds an allowable value.

In the first aspect of the present invention, it is preferable that the driving based on the limited amount of operation is disabled when the predetermined period has elapsed from the start time of the time measurement.

In the first aspect of the present invention, it is preferable that the limited amount of operation in a first half of the predetermined period is smaller than the limited amount of operation in a second half.

In the first aspect of the present invention, it is preferable that The construction machine control system, further comprises: a hydraulic system that includes a first hydraulic actuator for driving the boom and a second hydraulic actuator for driving the movable member, wherein in an excavation operation of the bucket, the hydraulic system is operated so that the boom is raised and the arm is lowered, and the hydraulic system is driven with the limited amount of operation when the arm is lowered.

In the first aspect of the present invention, it is preferable that the hydraulic system includes a control valve that adjusts an amount of operating oil supplied to the second hydraulic actuator, and the control signal is output to the control valve.

In the first aspect of the present invention, it is preferable that the hydraulic system includes: a hydraulic pump that supplies operating oil; and a pump control unit that controls the hydraulic pump so that the operating oil is supplied with a first largest discharge capacity from the hydraulic pump in a first operation mode and the operating oil is supplied with a second largest discharge capacity smaller than the first largest discharge capacity from the hydraulic pump in a second operation mode, and the limited amount of operation in the second operation mode is smaller than the limited amount of operation in the first operation mode.

In the first aspect of the present invention, it is preferable that the movable member is replaceable, and the limited amount of operation when the movable member of a first weight is connected to the boom is smaller than the limited amount of operation when the movable member of a second weight smaller than the first weight is connected.

In the first aspect of the present invention, it is preferable that the output of the control signal is started so that the movable member is driven with the limited amount of operation when an amount of increase per unit time of the detection value of the detection device exceeds an allowable value, and the amount of increase includes a difference between the amount of operation of the operating device and a processing amount generated by low-pass filtering of the amount of operation.

In the first aspect of the present invention, it is preferable that when the operating device is operated so that the amount of operation decreases, the limited amount of operation is maintained to a certain value from a decrease start time.

In the first aspect of the present invention, it is preferable that the movable member is driven based on the amount of operation when the amount of operation is smaller than the limited amount of operation.

In the first aspect of the present invention, it is preferable that the construction machine includes a vehicle body that supports the boom, and the limited amount of operation when the work machine is driven so that a distance between the bucket and a reference position of the vehicle body is a first distance is smaller than the limited amount of operation when the work machine is driven so that the distance between the bucket and the reference position is a second distance shorter than the first distance.

A second aspect of the present invention provides a construction machine comprising: a lower traveling structure; an upper revolving structure that is supported by the lower traveling structure; a work machine that includes a boom, an arm and a bucket and is supported by the upper revolving structure; and the control system of the first aspect of the present invention.

A third aspect of the present invention provides a method of controlling a construction machine that includes a work machine including a boom, an arm, and a bucket, the method comprising: determining a speed limit according to a distance between the bucket and a target excavation landform indicating a target shape of an excavation object based on the target excavation landform and bucket position data indicating a position of the bucket and limiting a speed of the boom so that a speed at which the work machine approaches the target excavation landform is equal to or smaller than the speed limit; operating an operating device in order to drive a movable member including at least one of the arm and the bucket; detecting an amount of operation of the operating device; setting a limited amount of operation for limiting a speed of the movable member based on a detection result of the detection device; and outputting a control signal so that the movable member is driven with the limited amount of operation.

Advantageous Effects of Invention

According to the aspects of the present invention, a decrease in excavation accuracy is suppressed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating an example of a construction machine.

FIG. 2 is a side view schematically illustrating an example of the construction machine.

FIG. 3 is a rear view schematically illustrating an example of the construction machine.

FIG. 4A is a block diagram illustrating an example of a control system.

FIG. 4B is a block diagram illustrating an example of a control system.

FIG. 5 is a schematic view illustrating an example of target construction information.

FIG. 6 is a flowchart illustrating an example of limited excavation control.

FIG. 7 is a diagram for describing an example of limited excavation control.

FIG. 8 is a diagram for describing an example of limited excavation control.

FIG. 9 is a diagram for describing an example of limited excavation control.

FIG. 10 is a diagram for describing an example of limited excavation control.

FIG. 11 is a diagram for describing an example of limited excavation control.

FIG. 12 is a diagram for describing an example of limited excavation control.

FIG. 13 is a diagram for describing an example of limited excavation control.

FIG. 14 is a diagram for describing an example of limited excavation control.

FIG. 15 is a diagram illustrating an example of a hydraulic cylinder.

FIG. 16 is a diagram illustrating an example of a cylinder stroke sensor.

FIG. 17 is a diagram illustrating an example of a control system.

FIG. 18 is a diagram illustrating an example of a control system.

FIG. 19 is a schematic diagram illustrating an example of an operation of a construction machine.

FIG. 20 is a functional block diagram illustrating an example of a control system.

FIG. 21 is a flowchart illustrating an example of a method of controlling the construction machine.

FIG. 22 is a diagram for describing an example of a method of controlling the construction machine.

FIG. 23 is a diagram for describing an example of a method of controlling the construction machine.

FIG. 24 is a diagram for describing an example of a method of controlling the construction machine.

FIG. 25 is a functional block diagram illustrating an example of a control system.

FIG. 26 is a diagram for describing an example of a method of controlling the construction machine.

FIG. 27 is a diagram for describing an example of a method of controlling the construction machine.

FIG. 28 is a diagram for describing an example of a method of controlling the construction machine.

FIG. 29 is a diagram for describing an example of a method of controlling the construction machine.

FIG. 30 is a functional block diagram illustrating an example of a control system.

FIG. 31 is a diagram for describing an example of a method of controlling the construction machine.

FIG. 32 is a diagram for describing an example of a method of controlling the construction machine.

FIG. 33 is a flowchart illustrating an example of a method of controlling the construction machine.

FIG. 34 is a diagram for describing an example of a method of controlling the construction machine.

FIG. 35 is a diagram for describing an example of a method of controlling the construction machine.

FIG. 36 is a diagram for describing an example of a method of controlling the construction machine.

FIG. 37 is a diagram for describing an example of a method of controlling the construction machine.

FIG. 38 is a functional block diagram illustrating an example of a control system.

FIG. 39 is a flowchart illustrating an example of a method of controlling the construction machine.

FIG. 40 is a diagram for describing an example of a method of controlling the construction machine.

FIG. 41 is a diagram for describing an example of a method of controlling the construction machine.

FIG. 42 is a diagram for describing an example of a method of controlling the construction machine.

FIG. 43 is a functional block diagram illustrating an example of a control system.

FIG. 44 is a schematic diagram illustrating an example of an operation of the construction machine.

FIG. 45 is a diagram for describing an example of a method of controlling the construction machine.

FIG. 46 is a diagram for describing an example of a method of controlling the construction machine.

FIG. 47 is a diagram for describing an example of a method of controlling the construction machine.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments according to the present invention are described with reference to the drawings, and the present invention is not limited thereto. Constituent components of the respective embodiments described hereinafter may be appropriately combined with each other. Moreover, some constituent components may be not used.

Overall Structure of Excavator

FIG. 1 is a perspective view illustrating an example of a construction machine 100 according to the present embodiment. In the present embodiment, an example in which the construction machine 100 is an excavator 100 that includes a work machine 2 operating with hydraulic pressure.

As illustrated in FIG. 1, the excavator 100 includes a vehicle body 1 and the work machine 2. As will be described later, a control system 200 that executes excavation control is mounted on the excavator 100.

The vehicle body 1 includes a revolving structure 3, a cab 4, and a traveling device 5. The revolving structure 3 is disposed on the traveling device 5. The traveling device 5 supports the revolving structure 3. The revolving structure 3 may be referred to as an upper revolving structure 3. The traveling device 5 may be referred to as a lower traveling structure 5. The revolving structure 3 can revolve about a revolution axis AX. A driver's seat 4S on which an operator sits is provided in the cab 4. The operator operates the excavator 100 in the cab 4. The traveling device 5 includes a pair of crawler belts 5Cr. With rotation of the crawler belts 5Cr, the excavator 100 travels. The traveling device 5 may include wheels (tires).

In the present embodiment, a positional relation of respective portions is described based on the driver's seat 4S. A front-rear direction is defined based on the driver's seat 4S. A left-right direction is defined based on the driver's seat 4S. A direction in which the driver's seat 4S faces the front is defined as a front direction and a direction opposite to the front direction is defined as a rear direction. The right and left sides in a lateral direction when the driver's seat 4S faces the front are defined as right and left directions, respectively.

The revolving structure 3 includes an engine room 9 in which an engine is stored and a counterweight provided at the rear portion of the revolving structure 3. A handrail 19 is provided in a portion of the revolving structure 3 on the front side of the engine room 9. An engine, a hydraulic pump, and the like are disposed in the engine room 9.

The work machine 2 is supported by the revolving structure 3. The work machine 2 includes a boom 6 connected to the revolving structure 3, an arm 7 connected to the boom 6, a bucket 8 connected to the arm 7, a boom cylinder 10 driving the boom 6, an arm cylinder 11 driving the arm 7, and a bucket cylinder 12 driving the bucket 8. The boom cylinder 10, the arm cylinder 11, and the bucket cylinder 12 are hydraulic cylinders driven by operating oil.

A base end of the boom 6 is connected to the revolving structure 3 with a boom pin 13 interposed. A base end of the arm 7 is connected to a distal end of the boom 6 with an arm pin 14 interposed. The bucket 8 is connected to a distal end of the arm 7 with a bucket pin 15 interposed. The boom 6 can rotate about the boom pin 13. The arm 7 can rotate about the arm pin 14. The bucket 8 can rotate about the bucket pin 15. The arm 7 and the bucket 8 are movable members that can move on the distal end side of the boom 6.

FIG. 2 is a side view schematically illustrating the excavator 100 according to the present embodiment. FIG. 3 is a rear view schematically illustrating the excavator 100 according to the present embodiment. As illustrated in FIG. 2, the length L1 of the boom 6 is the distance between the boom pin 13 and the arm pin 14. The length L2 of the arm 7 is the distance between the arm pin 14 and the bucket pin 15. The length L3 of the bucket 8 is the distance between the bucket pin 15 and a distal end 8 a of the bucket 8. In the present embodiment, the bucket 8 has a plurality of teeth. In the following description, the distal ends 8 a of the bucket 8 will be appropriately referred to as cutting edges 8 a.

The bucket 8 may not have teeth. The distal end of the bucket 8 may be formed of a straight steel plate.

As illustrated in FIG. 2, the excavator 100 includes a first cylinder stroke sensor 16 disposed in the boom cylinder 10, a second cylinder stroke sensor 17 disposed in the arm cylinder 11, and a third cylinder stroke sensor 18 disposed in the bucket cylinder 12. A stroke length of the boom cylinder 10 is obtained based on a detection result of the first cylinder stroke sensor 16. A stroke length of the arm cylinder 11 is obtained based on a detection result of the second cylinder stroke sensor 17. A stroke length of the bucket cylinder 12 is obtained based on a detection result of the third cylinder stroke sensor 18.

In the following description, the stroke length of the boom cylinder 10 will be appropriately referred to as a boom cylinder length, the stroke length of the arm cylinder 11 will be appropriately referred to as an arm cylinder length, and the stroke length of the bucket cylinder 12 will be appropriately referred to as a bucket cylinder length. Moreover, in the following description, the boom cylinder length, the arm cylinder length, and the bucket cylinder length will be appropriately collectively referred to as cylinder length data L.

The excavator 100 includes a position detection device 20 that can detect the position of the excavator 100. The position detection device 20 includes an antenna 21, a global coordinate calculating unit 23, and an inertial measurement unit (IMU) 24.

The antenna 21 is a global navigation satellite systems (GNSS) antenna. The antenna 21 is a real time kinematic-global navigation satellite systems (RTK-GNSS) antenna. The antenna 21 is provided in the revolving structure 3. In the present embodiment, the antenna 21 is provided in the handrail 19 of the revolving structure 3. The antenna 21 may be provided in a rear direction of the engine room 9. For example, the antenna 21 may be provided in the counterweight of the revolving structure 3. The antenna 21 outputs a signal corresponding to a received radio wave (GNSS radio wave) to the global coordinate calculating unit 23.

The global coordinate calculating unit 23 detects an installed position P1 of the antenna 21 in a global coordinate system. The global coordinate system is a 3-dimensional coordinate system based on a reference position Pr set in a work area. As illustrated in FIG. 2, in the present embodiment, the reference position Pr is the position of a distal end of a reference post set in a work area.

The global coordinate system is a coordinate system based on the origin Pr (see FIG. 2) fixed on the earth. A local coordinate system is a coordinate system based on the origin P2 (see FIG. 2) fixed to the vehicle body 1 of the construction machine 100. The local coordinate system may be referred to as a vehicle body coordinate system.

In FIG. 2 and other figures, the global coordinate system is represented by an XgYgZg orthogonal coordinate system. A reference position (origin) Pr of the global coordinate system is positioned in a work area. A direction within a horizontal plane is defined as an Xg-axis direction, a direction orthogonal to the Xg-axis direction within the horizontal plane is defined as a Yg-axis direction, and a direction orthogonal to the Xg-axis direction and the Yg-axis direction is defined as a Zg-axis direction. Moreover, rotational (tilt) directions about the Xg, Yg, and Zg-axes are defined as θXg, θYg, and θZg-directions, respectively. The Xg-axis is orthogonal to a YgZg plane. The Yg-axis is orthogonal to an XgZg plane. The Zg-axis is orthogonal to an XgYg plane. The XgYg plane is parallel to the horizontal plane. The Zg-axis direction is a vertical direction.

In FIG. 2 and other figures, the local coordinate system is represented by an XYZ orthogonal coordinate system. The reference position (origin) P2 of the local coordinate system is positioned at the revolution center AX of the revolving structure 3. A direction within a certain plane is defined as an X-axis direction, a direction orthogonal to the X-axis direction within the plane is defined as a Y-axis direction, and a direction orthogonal to the X-axis direction and the Y-axis direction is defined as a Z-axis direction. Moreover, rotational (tilt) directions about the X, Y, and Z-axes are defined as θX, θY, and θZ-directions, respectively. The X-axis is orthogonal to the YZ plane. The Y-axis is orthogonal to the XZ plane. The Z-axis is orthogonal to the XY plane.

In the present embodiment, the antenna 21 includes a first antenna 21A and a second antenna 21B provided in the revolving structure 3 so as to be separated in a vehicle width direction. The first antenna 21A and the second antenna 21B detect installed positions P1 a and P1 b, respectively, and output the same to the global coordinate calculating unit 23.

The global coordinate calculating unit 23 acquires reference position data P represented by a global coordinate. In the present embodiment, the reference position data P is data indicating the reference position P2 positioned at the revolution axis (revolution center) AX of the revolving structure 3. The reference position data P may be data indicating the installed position P1. In the present embodiment, the global coordinate calculating unit 23 generates revolving structure direction data Q based on two installed positions P1 a and P1 b. The revolving structure direction data Q is determined based on an angle between a reference direction (for example, the north) of the global coordinate and a line determined by the installed positions P1 a and P1 b. The revolving structure direction data Q indicates a direction in which the revolving structure 3 (the work machine 2) faces. The global coordinate calculating unit 23 outputs the reference position data P and the revolving structure direction data Q to a display controller 28 (described later).

The IMU 24 is provided in the revolving structure 3. In the present embodiment, the IMU 24 is disposed under the cab 4. A high-rigidity frame is disposed in a portion of the revolving structure 3 under the cab 4. The IMU 24 is disposed on the frame. The IMU 24 may be disposed on a lateral side (right or left side) of the revolution axis AX (the reference position P2) of the revolving structure 3. The IMU 24 detects a tilt angle θ4 in the left-to-right direction of the vehicle body 1 and a tilt angle θ5 in the front-rear direction of the vehicle body 1 in relation to the global coordinate.

Configuration of Control System

Next, an overview of the control system 200 according to the present embodiment will be described. FIG. 4A is a block diagram illustrating a functional configuration of the control system 200 according to the present embodiment.

The control system 200 controls an excavation process of using the work machine 2. The control of excavation process includes limited excavation control. As illustrated in FIG. 4A, the control system 200 includes the first cylinder stroke sensor 16, the second cylinder stroke sensor 17, the third cylinder stroke sensor 18, the antenna 21, the global coordinate calculating unit 23, the IMU 24, an operating device 25, a work machine controller 26, pressure sensors 66 and 67, a control valve 27, a direction control valve 64, the display controller 28, a display unit 29, a sensor controller 30, and a man machine interface 32 that sets an operation mode.

The operating device 25 is disposed in the cab 4.

The operating device 25 is operated by an operator. The operating device 25 receives an operator operation that drives the work machine 2. In the present embodiment, the operating device 25 is a pilot hydraulic-type operating device.

In the following description, oil supplied to hydraulic cylinders (the boom cylinder 10, the arm cylinder 11, and the bucket cylinder 12) in order to operate the hydraulic cylinders will be appropriately referred to as operating oil. In the present embodiment, the amount of operating oil supplied to the hydraulic cylinder is adjusted by the direction control valve 64. The direction control valve 64 operates with oil supplied. In the following description, oil supplied to the direction control valve 64 in order to operate the direction control valve 64 will be appropriately referred to as pilot oil. Moreover, the pressure of pilot oil will be appropriately referred to as pilot pressure.

The operating oil and the pilot oil may be delivered from the same hydraulic pump. For example, a portion of the operating oil delivered from the hydraulic pump is decompressed and the decompressed operating oil may be used as the pilot oil. Moreover, a hydraulic pump (main hydraulic pump) that delivers operating oil and a hydraulic pump (pilot hydraulic pump) that delivers pilot oil may be different hydraulic pumps.

The operating device 25 includes a first operating lever 25R and a second operating lever 25L. The first operating lever 25R is disposed on the right side of the driver's seat 4S, for example. The second operating lever 25L is disposed on the left side of the driver's seat 4S, for example. In the first and second operating levers 25R and 25L, the front-rear and left-right movements correspond to 2-axis operations.

The boom 6 and the bucket 8 are operated by the first operating lever 25R. The operation in the front-rear direction of the first operating lever 25R corresponds to an operation of the boom 6, and a lowering operation and a raising operation of the boom 6 are executed according to the operation in the front-rear direction. The operation in the left-right direction of the first operating lever 25R corresponds to an operation of the bucket 8, and an excavating operation and a releasing operation of the bucket 8 are executed according to the operation in the left-right direction.

The arm 7 and the revolving structure 3 are operated by the second operating lever 25L. The operation in the front-rear direction of the second operating lever 25L corresponds to an operation of the arm 7, and a raising operation and a lowering operation of the arm 7 are executed according to the operation in the front-rear direction. The operation in the left-right direction of the second operating lever 25L corresponds to revolving of the revolving structure 3, and a right revolving operation and a left revolving operation of the revolving structure 3 are executed according to the operation in the left-right direction.

In the present embodiment, the raising operation of the boom 6 corresponds to a dumping operation. The lowering operation of the boom 6 corresponds to an excavating operation. The lowering operation of the arm 7 corresponds to an excavating operation. The raising operation of the arm 7 corresponds to a dumping operation. The lowering operation of the bucket 8 corresponds to an excavating operation. The lowering operation of the arm 7 may be referred to as a bending operation. The raising operation of the arm 7 may be referred to as an extending operation.

The pilot oil which has been delivered from the hydraulic pump and decompressed to pilot pressure by the pressure-reducing valve is supplied to the operating device 25. The pilot pressure is adjusted by the amount of operation of the operating device 25, and the direction control valve 64 via which operating oil supplied to the hydraulic cylinders (the boom cylinder 10, the arm cylinder 11, and the bucket cylinder 12) is driven with the pilot pressure. The pressure sensors 66 and 67 are disposed in pilot pressure lines 450. The pressure sensors 66 and 67 detect the pilot pressure. The detection results of the pressure sensors 66 and 67 are output to the work machine controller 26.

The first operating lever 25R is operated in the front-rear direction in order to drive the boom 6. The direction control valve 64 via which the operating oil supplied to the boom cylinder 10 for driving the boom 6 is driven according to an amount of operation (amount of boom operation) of the first operating lever 25R in the front-rear direction. Moreover, the pressure generated in the sensor 66 during this lever operation is referred to an amount of boom lever operation MB.

The first operating lever 25R is operated in the left-right direction in order to drive the bucket 8. The direction control valve 64 via which the operating oil supplied to the bucket cylinder 12 for driving the bucket 8 is driven according to the amount of operation (amount of bucket operation) of the first operating lever 25R in the left-right direction. Moreover, the pressure generated in the sensor 66 during this lever operation is referred to as an amount of bucket lever operation MT.

The second operating lever 25L is operated in the front-rear direction in order to drive the arm 7. The direction control valve 64 via which the operating oil supplied to the arm cylinder 11 for driving the arm 7 is driven according to an amount of operation (amount of arm operation) of the second operating lever 25L in the front-rear direction. Moreover, the pressure generated in the sensor 66 during this lever operation is referred to as an amount of arm lever operation MA.

The second operating lever 25L is operated in the left-right direction in order to drive the revolving structure 3. The direction control valve 64 via which the operating oil supplied to a hydraulic actuator for driving the revolving structure 3 is driven according to the amount of operation of the second operating lever 25L in the left-right direction.

The operation in the left-right direction of the first operating lever 25R may correspond to the operation of the boom 6, and the operation in the front-rear direction may correspond to the operation of the bucket 8. The operation in the left-right direction of the second operating lever 25L may correspond to the operation of the arm 7, and the operation in the front-rear direction may correspond to the operation of the revolving structure 3.

The control valve 27 operates in order to adjust the amount of operating oil supplied to the hydraulic cylinders (the boom cylinder 10, the arm cylinder 11, and the bucket cylinder 12). The control valve 27 operates based on a control signal from the work machine controller 26.

The sensor controller 30 calculates a boom cylinder length based on a detection result of the first cylinder stroke sensor 16. The first cylinder stroke sensor 16 outputs a phase shift pulse associated with the revolving operation to the sensor controller 30. The sensor controller 30 calculates the boom cylinder length based on the phase shift pulse output from the first cylinder stroke sensor 16. Similarly, the sensor controller 30 calculates an arm cylinder length based on a detection result of the second cylinder stroke sensor 17. The sensor controller 30 calculates a bucket cylinder length based on a detection result of the third cylinder stroke sensor 18.

The sensor controller 30 calculates a tilt angle θ1 of the boom 6 with respect to the vertical direction of the revolving structure 3 from the boom cylinder length acquired based on the detection result of the first cylinder stroke sensor 16. The sensor controller 30 calculates a tilt angle θ2 of the arm 7 with respect to the boom 6 from the arm cylinder length acquired based on the detection result of the second cylinder stroke sensor 17. The sensor controller 30 calculates a tilt angle θ3 of the cutting edge 8 a of the bucket 8 with respect to the arm 7 from the bucket cylinder length acquired based on the detection result of the third cylinder stroke sensor 18.

The tilt angle θ1 of the boom 6, the tilt angle θ2 of the arm 7, and the tilt angle θ3 of the bucket 8 may not be detected by the cylinder stroke sensors. The tilt angle θ1 of the boom 6 may be detected by an angle detection device such as a rotary encoder. The angle detection device detects a bending angle of the boom 6 with respect to the revolving structure 3 to detect the tilt angle θ1. Similarly, the tilt angle θ2 of the arm 7 may be detected by an angle detection device attached to the arm 7. The tilt angle θ3 of the bucket 8 may be detected by an angle detection device attached to the bucket 8.

FIG. 4B is a block diagram illustrating the work machine controller 26, the display controller 28, and the sensor controller 30. The sensor controller 30 acquires a cylinder length data L from the detection results of the first, second, and third cylinder stroke sensors 16, 17, and 18. The sensor controller 30 outputs the data of the tilt angle θ4 and the data of the tilt angle θ5 of the vehicle body 1 output from the IMU 24. The sensor controller 30 outputs the data of the tilt angles θ1 to θ3 and the data of the tilt angle θ5 of the respective work machines to the display controller 28 and the work machine controller 26, respectively.

As described above, in the present embodiment, the detection results of the cylinder stroke sensors (16, 17, and 18) and the detection result of the IMU 24 are output to the sensor controller 30, and the sensor controller 30 performs a predetermined calculating process. In the present embodiment, the functions of the sensor controller 30 may be performed by the work machine controller 26. For example, the detection results of the cylinder stroke sensors (16, 17, and 18) may be output to the work machine controller 26, and the work machine controller 26 may calculate the cylinder lengths (the boom cylinder length, the arm cylinder length, and the bucket cylinder length) based on the detection results of the cylinder stroke sensors (16, 17, and 18). The detection result of the IMU 24 may be output to the work machine controller 26.

The display controller 28 includes a target construction information storage unit 28A, a bucket position data generating unit 28B, and a target excavation landform data generating unit 28C. The display controller 28 acquires the reference position data P and the revolving structure direction data Q from the global coordinate calculating unit 23. The display controller 28 acquires cylinder tilt data θ1 to θ3 from the sensor controller 30.

The bucket position data generating unit 28B generates bucket position data indicating a 3-dimensional position of the bucket 8 based on the reference position data P, the revolving structure direction data Q, and the cylinder tilt data θ1 to θ3. In the present embodiment, the bucket position data is cutting edge position data S indicating a 3-dimensional position of the cutting edge 8 a.

The target excavation landform data generating unit 28C generates a target excavation landform U indicating a target shape of an excavation object using the cutting edge position data S and target construction information T (described later) stored in the target construction information storage unit 28A. Moreover, the display controller 28 displays the target excavation landform U on the display unit 29 based on the target excavation landform U. The display unit 29 is a monitor, for example, and displays various types of information of the excavator 100. In the present embodiment, the display unit 29 includes a human machine interface (HMI) monitor as a guidance monitor for information-oriented construction.

The display controller 28 can calculate the local coordinate position when seen in the global coordinate system based on the detection result of the position detection device 20. The local coordinate system is a 3-dimensional coordinate system based on the excavator 100. The reference position of the local coordinate system is the reference position P2 positioned at the revolution axis AX of the revolving structure 3, for example.

The target construction information storage unit 28A stores target construction information (3-dimensional designed landform data) T indicating a 3-dimensional designed landform which is a target shape of a work area. The target construction information T includes coordinate data and angle data required in order to generate the target excavation landform (designed landform data) U indicating a designed landform which is a target shape of an excavation object. The target construction information T may be supplied to the display controller 28 via a radio communication device, for example. The target construction information T may be transmitted from a connection-type recording device such as a memory.

The target excavation landform data generating unit 28C calculates the position P3 of the bucket cutting edge 8 a in the global coordinate system in relation to the reference position P2 of the global coordinate system from the tilt angle θ1 of the boom 6, the tilt angle θ2 of the arm 7, the tilt angle θ3 of the bucket 8, the length L1 of the boom 6, the length L2 of the arm 7, the length L3 of the bucket 8, and the position information of the boom pin 13. The target excavation landform data generating unit 28C acquires a nodal line E between the 3-dimensional designed landform and a working plane MP of the work machine 2 defined in the front-rear direction of the revolving structure 3 as illustrated in FIG. 5 as a candidate line based on the target construction information T and the cutting edge position data 8 a. The target excavation landform data generating unit 28C sets a point of the candidate line of the target excavation landform U located immediately below the bucket cutting edge 8 a as a reference point AP of the target excavation landform U. The target excavation landform data generating unit 28C determines a single or a plurality of inflection points appearing before and after the reference point AP of the target excavation landform U and lines appearing before and after the inflection points as the target excavation landform U which serves as an excavation object. The target excavation landform data generating unit 28C generates the target excavation landform U indicating a designed landform which is a target shape of the excavation object. A relative distance d between the target excavation landform U and the cutting edge 8 a is acquired based on the target excavation landform U and the bucket cutting edge 8 a.

The target excavation landform data generating unit 28C outputs the target excavation landform U, the bucket cutting edge 8 a, and the distance between the target excavation landform U and the bucket cutting edge 8 a to the display unit 29. The display unit 29 displays a positional relation between the target excavation landform and the bucket 8 as an image and displays the distance d between the target excavation landform U and the bucket cutting edge 8 a. Moreover, the target excavation landform data generating unit 28C outputs the calculated target excavation landform U to the work machine controller 26.

The man machine interface 32 includes an input unit and a display unit. The display unit includes a monitor such as a flat panel display. The input unit of the man machine interface 32 includes operation buttons arranged around the display unit of the man machine interface 32. The input unit of the man machine interface 32 may include a touch panel. The man machine interface 32 may be referred to a multi-monitor 32. The input unit of the man machine interface 32 is operated by an operator. A command signal generated according to operations on the input unit is output to the work machine controller 26. The work machine controller 26 controls the display unit of the man machine interface 32 to display predetermined information on the display unit.

Limited Excavation Control

Next, an example of limited excavation control according to the present embodiment will be described. The work machine controller 26 includes a target speed determining unit 52 that determines a target speed of the bucket 8 determined according to the amount of operation of the operating device 25, a distance acquiring unit 53, a speed limit determining unit 54, a work machine control unit 57, and an arm control unit 263. The work machine controller 26 derives the position P3 of the cutting edge 8 a in the local coordinate system from the tilt angles θ1, θ2, and θ3, the position information of the boom pin 13, the angle θ5 output from the IMU 24, the detection result of the position detection device 20, and the position information of the antenna 21 with the aid of the sensor controller 30. The work machine controller 26 acquires the cutting edge position information independently from the display controller 28.

The target speed determining unit 52 acquires the tilt angle θ5 in the front-rear direction of the vehicle body 1 and the amounts of operation MB, MA, and MT acquired from the sensor 66 as Vc_bm, Vc_am, and Vc_bk corresponding to the lever operation for driving the respective work machines of the boom 6, the arm 7, and the bucket 8. The distance acquiring unit 53 acquires the target excavation landform U from the display controller 28. The distance acquiring unit 53 calculates the distance d between the cutting edge 8 a of the bucket 8 and the target excavation landform U in the direction vertical to the target excavation landform U based on the cutting edge position data P3 and the target excavation landform U. The speed limit determining unit 54 limits the movement of the boom 6 based on the distance d and the target speed. The work machine control unit 57 determines an intervention command CBI on an intervention valve 27C with respect to a speed limit Vc_bm_lmt. An intervention speed of the boom 6 is output according to the above commands, whereby the work machine controller 28 executes limited excavation control (intervention control).

The arm control unit 263 acquires the amount of operation MA of the arm 7 from the target speed determining unit 52. When it is determined that it is necessary to limit the operation on the arm 7, which will be described later, a speed limit Vc_am_lmt is output to the work machine control unit 57. The work machine control unit 57 outputs a deceleration command CA to the control valve 27 (27A and 27B) according to the speed limit Vc_am_lmt. The limitation determination of the arm control unit 263 will be described in detail later.

Hereinafter, an example of limited excavation control according to the present embodiment will be described with reference to the flowchart of FIG. 6 and the schematic diagrams of FIGS. 7 to 14. FIG. 6 is a flowchart illustrating an example of limited excavation control according to the present embodiment.

As described above, the target excavation landform U is set (step SA1). After the target excavation landform U is set, the work machine controller 26 determines the target speed Vc of the work machine 2 (step SA2). The target speed Vc of the work machine 2 includes a boom target speed Vc_bm, an arm target speed Vc_am, and a bucket target speed Vc_bkt. The boom target speed Vc_bm is the speed of the cutting edge 8 a when the boom cylinder 10 only is driven. The arm target speed Vc_am is the speed of the cutting edge 8 a when the arm cylinder 11 only is driven. The bucket target speed Vc_bkt is the speed of the cutting edge 8 a when the bucket cylinder 12 only is driven. The boom target speed Vc_bm is calculated based on the amount of boom operation. The arm target speed Vc_am is calculated based on the amount of arm operation. The bucket target speed Vc_bkt is calculated based on the amount of bucket operation.

Target speed information that defines the relation between the amount of boom operation and the boom target speed Vc_bm is stored in a storage unit 264 of the work machine controller 26. The work machine controller 26 determines the boom target speed Vc_bm corresponding to the amount of boom operation based on the target speed information. The target speed information is a map in which the magnitude of the boom target speed Vc_bm corresponding to the amount of boom operation, for example, is described. The target speed information may be in the form of a table, a numerical expression, or the like. The target speed information includes information that defines the relation between the amount of arm operation and the arm target speed Vc_am. The target speed information includes information that defines the relation between the amount of bucket operation and the bucket target speed Vc_bkt. The work machine controller 26 determines the arm target speed Vc_am corresponding to the amount of arm operation based on the target speed information. The work machine controller 26 determines the bucket target speed Vc_bkt corresponding to the amount of bucket operation based on the target speed information.

As illustrated in FIG. 7, the work machine controller 26 converts the boom target speed Vc_bm into a speed component (vertical speed component) Vcy_bm in the direction vertical to the surface of the target excavation landform U and a speed component (horizontal speed component) Vcx_bm in the direction parallel to the surface of the target excavation landform U (step SA3).

The work machine controller 26 calculates an inclination of the vertical axis (the revolution axis AX of the revolving structure 3) of the local coordinate system with respect to the vertical axis of the global coordinate system and an inclination in the vertical direction of the surface of the target excavation landform U with respect to the vertical axis of the global coordinate system from the reference position data P, the target excavation landform U, and the like. The work machine controller 26 calculates an angle β1 indicating the inclination between the vertical axis of the local coordinate system and the vertical direction of the surface of the target excavation landform U from these inclinations.

As illustrated in FIG. 8, the work machine controller 26 converts the boom target speed Vc_bm into a speed component VL1_bm in the vertical axis direction of the local coordinate system and a speed component VL2_bm in the horizontal axis direction according to the theorem of trigonometric function from an angle β2 between the vertical axis of the local coordinate system and the direction of the boom target speed Vc_bm.

As illustrated in FIG. 9, the work machine controller 26 converts the speed component VL1_bm in the vertical axis direction of the local coordinate system and the speed component VL2_bm in the horizontal axis direction into a vertical speed component Vcy_bm and a horizontal speed component Vcx_bm with respect to the target excavation landform U according to the theorem of trigonometric function from the inclination β1 between the vertical axis of the local coordinate system and the vertical direction of the surface of the target excavation landform U. Similarly, the work machine controller 26 converts the arm target speed Vc_am into a vertical speed component Vcy_am and a horizontal speed component Vcx_am in the vertical axis direction of the local coordinate system. The work machine controller 26 converts the bucket target speed Vc_bkt into a vertical speed component Vcy_bkt and a horizontal speed component Vcx_bkt in the vertical axis direction of the local coordinate system.

As illustrated in FIG. 10, the work machine controller 26 acquires the distance d between the cutting edge 8 a of the bucket 8 and the target excavation landform U (step SA4). The work machine controller 26 calculates the shortest distance d between the surface of the target excavation landform U and the cutting edge 8 a of the bucket 8 from the position information of the cutting edge 8 a, the target excavation landform U, and the like. In the present embodiment, the limited excavation control is executed based on the shortest distance d between the surface of the target excavation landform U and the cutting edge 8 a of the bucket 8.

The work machine controller 26 calculates an overall speed limit Vcy_lmt of the work machine 2 based on the distance d between the surface of the target excavation landform U and the cutting edge 8 a of the bucket 8 (step SA5). The overall speed limit Vcy_lmt of the work machine 2 is an allowable moving speed of the cutting edge 8 a in the direction in which the cutting edge 8 a of the bucket 8 approaches the target excavation landform U. Speed limit information that defines the relation between the distance d and the speed limit Vcy_lmt is stored in the storage unit 264 of the work machine controller 26.

FIG. 11 illustrates an example of the speed limit information according to the present embodiment. In the present embodiment, the horizontal axis is the distance d and the vertical axis is the speed limit Vcy_lmt. The distance d has a positive value when the cutting edge 8 a is positioned on the outer side of the surface of the target excavation landform U (that is, on the side close to the work machine 2 of the excavator 100), and the distance d has a negative value when the cutting edge 8 a is positioned on the inner side of the surface of the target excavation landform U (that is, on the inner side of the excavation object than the target excavation landform U). As illustrated in FIG. 10, the distance d has a positive value when the cutting edge 8 a is positioned above the surface of the target excavation landform U. The distance d has a negative value when the cutting edge 8 a is positioned under the surface of the target excavation landform U. Moreover, the distance d has a positive value when the cutting edge 8 a is positioned at such a position that the cutting edge 8 a does not dig into the target excavation landform U. The distance d has a negative value when the cutting edge 8 a is positioned at such a position that the cutting edge 8 a digs into the target excavation landform U. The distance d is 0 when the cutting edge 8 a is positioned on the target excavation landform U (that is, when the cutting edge 8 a is in contact with the target excavation landform U).

In the present embodiment, the speed has a positive value when the cutting edge 8 a moves from the inner side of the target excavation landform U toward the outer side, and the speed has a negative value when the cutting edge 8 a moves from the outer side of the target excavation landform U toward the inner side. That is, the speed has a positive value when the cutting edge 8 a moves toward the upper side of the target excavation landform U, and the speed has a negative value when the cutting edge 8 a moves toward the lower side of the target excavation landform U.

In the speed limit information, an inclination of the speed limit Vcy_lmt when the distance d is between d1 and d2 is smaller than an inclination when the distance d is equal to or larger than d1 or equal to or smaller than d2. d1 is larger than 0. d2 is smaller than 0. In operations near the surface of the target excavation landform U, in order to set the speed limit more accurately, the inclination when the distance d is between d1 and d2 is smaller than the inclination when the distance d is equal to or larger than d1 or equal to or smaller than d2. The speed limit Vcy_lmt has a negative value when the distance d is equal to or larger than d1, and the larger the distance d, the smaller the speed limit Vcy_lmt. That is, when the distance d is equal to or larger than d1, the farther the cutting edge 8 a above the target excavation landform U from the surface of the target excavation landform U, the larger the speed of moving toward the lower side of the target excavation landform U and the larger the absolute value of the speed limit Vcy_lmt. When the distance d is equal to or smaller than 0, the speed limit Vcy_lmt has a positive value, and the smaller the distance d, the larger the speed limit Vcy_lmt. That is, when the distance d of the cutting edge 8 a of the bucket 8 from the target excavation landform U is equal to or smaller than 0, the farther the cutting edge 8 a on the lower side of the target excavation landform U from the target excavation landform U, the larger the speed of moving toward the upper side of the target excavation landform U, and the larger the absolute value of the speed limit Vcy_lmt.

When the distance d is equal to or larger than a predetermined value dth1, the speed limit Vcy_lmt is Vmin. The predetermined value dth1 is a positive value and is larger than d1. Vmin is smaller than a smallest value of the target speed. That is, when the distance d is equal to or larger than the predetermined value dth1, the operation of the work machine 2 is not limited. Thus, when the cutting edge 8 a is separated greatly from the target excavation landform U on the upper side of the target excavation landform U, the operation of the work machine 2 is not limited (that is, the limited excavation control is not performed). When the distance d is smaller than the predetermined value dth1, the operation of the work machine 2 is limited. When the distance d is smaller than the predetermined value dth1, the operation of the boom 6 is limited.

The work machine controller 26 calculates a vertical speed component (limited vertical speed component) Vcy_bm_lmt of the speed limit of the boom 6 from the overall speed limit Vcy_lmt of the work machine 2, the arm target speed Vc_am, and the bucket target speed Vc_bkt (step SA6).

As illustrated in FIG. 12, the work machine controller 26 calculates the limited vertical speed component Vcy_bm_lmt of the boom 6 by subtracting the vertical speed component Vcy_am of the arm target speed and the vertical speed component Vcy_bkt of the bucket target speed from the overall speed limit Vcy_lmt of the work machine 2.

As illustrated in FIG. 13, the work machine controller 26 converts the limited vertical speed component Vcy_bm_lmt of the boom 6 into a speed limit (boom speed limit) Vc_bm_lmt (step SA7). The work machine controller 26 obtains a relation between a direction vertical to the surface of the target excavation landform U and the direction of the boom speed limit Vc_bm_lmt from a rotation angle a of the boom 6, a rotation angle β of the arm 7, a rotation angle of the bucket 8, vehicle body position data P, the target excavation landform U, and the like and converts the limited vertical speed component Vcy_bm_lmt of the boom 6 into a boom speed limit Vc_bm_lmt. This calculation is performed in a reverse order to that of the calculation of calculating the vertical speed component Vcy_bm in the direction vertical to the surface of the target excavation landform U from the boom target speed Vc_bm. After that, a cylinder speed corresponding to a boom intervention amount is determined, and a release command corresponding to the cylinder speed is output to the intervention valve 27C described later.

The pilot pressure based on the lever operation is filled in an oil passage 451B and the pilot pressure based on boom intervention is filled in an oil passage 502. A shuttle valve 51 (described later) selects the larger pressure (step SA8).

For example, when no intervention is performed on the boom 6, and the magnitude of the boom speed limit Vc_bm_lmt in the downward direction of the boom 6 is smaller than the magnitude of the boom target speed Vc_bm in the downward direction, limiting conditions are not satisfied. Moreover, when the boom 6 is raised by performing intervention on the boom 6, and the magnitude of the boom speed limit Vc_bm_lmt in the upward direction of the boom 6 is larger than the magnitude of the boom target speed Vc_bm in the upward direction, the limiting conditions are satisfied.

The work machine controller 26 controls the work machine 2. When controlling the boom 6, the work machine controller 26 controls the boom cylinder 10 by transmitting a boom command signal to the intervention valve 27C. The boom command signal has a current value corresponding to a boom command speed.

When the limiting conditions are not satisfied, the shuttle valve 51 selects the supply of operating oil from the oil passage 451B, and a normal operation is performed (step SA9). The work machine controller 26 operates the boom cylinder 10, the arm cylinder 11, and the bucket cylinder 12 according to the amount of boom operation, the amount of arm operation, and the amount of bucket operation, respectively. The boom cylinder 10 operates at the boom target speed Vc_bm. The arm cylinder 11 operates at the arm target speed Vc_am. The bucket cylinder 12 operates at the bucket target speed Vc_bkt.

When the limiting conditions are satisfied, the shuttle valve 51 selects the supply of operating oil from an oil passage 502, and the limited excavation control is executed (step SA10).

The limited vertical speed component Vcy_bm_lmt of the boom 6 is calculated by subtracting the vertical speed component Vcy_am of the arm target speed and the vertical speed component Vcy_bkt of the bucket target speed from the overall speed limit Vcy_lmt of the work machine 2. Thus, when the overall speed limit Vcy_lmt of the work machine 2 is smaller than the sum of the vertical speed component Vcy_am of the arm target speed and the vertical speed component Vcy_bkt of the bucket target speed, the limited vertical speed component Vcy_bm_lmt of the boom 6 has a negative value, in which case the boom is raised.

In this case, the work machine controller 27 lowers the boom 6 at a speed lower than the boom target speed Vc_bm. Thus, it is possible to prevent the bucket 8 from digging into the target excavation landform U while suppressing the sense of incongruity the operator might feel.

When the overall speed limit Vcy_lmt of the work machine 2 is larger than the sum of the vertical speed component Vcy_am of the arm target speed and the vertical speed component Vcy_bkt of the bucket target speed, the limited vertical speed component Vcy_bm_lmt of the boom 6 has a positive value. Thus, the boom speed limit Vc_bm_lmt has a positive value. In this case, even when the operating device 25 is operated in a direction where the boom 6 is lowered, the work machine controller 26 raises the boom 6. Thus, it is possible to quickly suppress expansion of a digging area of the target excavation landform U.

When the cutting edge 8 a is positioned above the target excavation landform U, the closer the cutting edge 8 a approaches the target excavation landform U, the smaller the absolute value of the limited vertical speed component Vcy_bm_lmt of the boom 6, and the smaller the absolute value of the speed component (limited horizontal speed component) Vcx_bm_lmt of the speed limit of the boom 6 in the direction parallel to the surface of the target excavation landform U. Thus, when the cutting edge 8 a is positioned above the target excavation landform U, the closer the cutting edge 8 a approaches the target excavation landform U, the more the speed of the boom 6 in the direction vertical to the surface of the target excavation landform U and the speed of the boom 6 in the direction parallel to the surface of the target excavation landform U are decelerated. When the left operating lever 25L and the right operating lever 25R are operated simultaneously by the operator of the excavator 100, the boom 6, the arm 7, and the bucket 8 are operated simultaneously. In this case, the above-described control when target speeds Vc_bm, Vc_am, and Vc_bkt of the boom 6, the arm 7, and the bucket 8 are input will be described below.

FIG. 14 illustrates an example of a change in the speed limit of the boom 6 when the distance d between the target excavation landform U and the cutting edge 8 a of the bucket 8 is smaller than the predetermined value dth1 and the cutting edge 8 a of the bucket 8 moves from the position Pn1 to the position Pn2. The distance between the cutting edge 8 a and the target excavation landform U at the position Pn2 is smaller than the distance between the cutting edge 8 a and the target excavation landform U at the position Pn1. Due to this, the limited vertical speed component Vcy_bm_lmt2 of the boom 6 at the position Pn2 is smaller than the limited vertical speed component Vcy_bm_lmt1 of the boom 6 at the position Pn1. Thus, the boom speed limit Vc_bm_lmt2 at the position Pn2 is smaller than the boom speed limit Vc_bm_lmt1 at the position Pn1. Moreover, the limited horizontal speed component Vcx_bm_lmt2 of the boom 6 at the position Pn2 is smaller than the limited horizontal speed component Vcx_bm_lmt1 of the boom 6 at the position Pn1. However, in this case, the arm target speed Vc_am and the bucket target speed Vc_bkt are not limited. Due to this, the vertical speed component Vcy_am and the horizontal speed component Vcx_am of the arm target speed and the vertical speed component Vcy_bkt and the horizontal speed component Vcx_bkt of the bucket target speed are not limited.

As described above, since no limitation is applied to the arm 7, a change in the amount of arm operation corresponding to the operator's intention to excavate is reflected as a change in the speed of the cutting edge 8 a of the bucket 8. Thus, the present embodiment can suppress the sense of incongruity during the excavation operation of the operator while suppressing expansion of a digging area of the target excavation landform U.

In this manner, in the present embodiment, the work machine controller 26 limits the speed of the boom 6 based on the target excavation landform U indicating the designed landform which is a target shape of an excavation object and the cutting edge position data S indicating the position of the cutting edge 8 a of the bucket 8 so that a relative speed at which the bucket 8 approaches the target excavation landform U decreases according to the distance d between the target excavation landform U and the cutting edge 8 a of the bucket 8. The work machine controller 26 determines the speed limit according to the distance d between the target excavation landform U and the cutting edge 8 a of the bucket 8 based on the target excavation landform U indicating the designed landform which is a target shape of an excavation object and the cutting edge position data S indicating the position of the cutting edge 8 a of the bucket 8 and controls the work machine 2 so that the speed in the direction in which the work machine 2 approaches the target excavation landform U is equal to or smaller than the speed limit. In this way, limited excavation control on the cutting edge 8 a is executed, and the position of the cutting edge 8 a in relation to the target excavation landform U is controlled.

In the following description, outputting a control signal to the control valve 27 connected to the boom cylinder 10 to control the position of the boom 6 so that digging of the cutting edge 8 a into the target excavation landform U is suppressed is referred to as intervention control.

The intervention control is executed when the relative speed of the cutting edge 8 a in the vertical direction in relation to the target excavation landform U is larger than the speed limit. The intervention control is not executed when the relative speed of the cutting edge 8 a is smaller than the speed limit. The fact that the relative speed of the cutting edge 8 a is smaller than the speed limit includes the fact that the bucket 8 moves in relation to the target excavation landform U so that the bucket 8 is separated from the target excavation landform U.

Moreover, the work machine controller 26 controls the arm 7 and the bucket 8. When an arm speed limit command is output from an arm control unit described later, the work machine controller 26 transmits an arm command signal CA to the control valve 27 (27A and 27B) to thereby limit the supply of pilot pressure that drives the arm cylinder 11. With limited supply of the pilot pressure, the driving of the arm cylinder 11 is limited. The arm command signal CA has a current value corresponding to an arm command speed. The work machine controller 26 transmits a bucket command signal to the control valve 27 to thereby control the bucket cylinder 12 similarly to the arm cylinder 11. The bucket command signal has a current value corresponding to a bucket command speed.

Cylinder Stroke Sensor

Next, the cylinder stroke sensor 16 will be described with reference to FIGS. 15 and 16. In the following description, the cylinder stroke sensor 16 attached to the boom cylinder 10 is described. The cylinder stroke sensor 17 and the like attached to the arm cylinder 11 have the same configuration as the cylinder stroke sensor 16.

The cylinder stroke sensor 16 is attached to the boom cylinder 10. The cylinder stroke sensor 16 measures the stroke of a piston. As illustrated in FIG. 15, the boom cylinder 10 includes a cylinder tube 10X and a cylinder rod 10Y configured to move within the cylinder tube 10X in relation to the cylinder tube 10X. A piston 10V is slidably provided in the cylinder tube 10X. The cylinder rod 10Y is attached to the piston 10V. The cylinder rod 10Y is slidably provided in a cylinder head 10W. A chamber formed by the cylinder head 10W, the piston 10V, and a cylinder inner wall is a rod-side oil chamber 40B. An oil chamber on the opposite side of the rod-side oil chamber 40B with the piston 10V interposed is a cab-side oil chamber 40A. A seal member is provided in the cylinder head 10W so as to seal the gap between the cylinder head 10W and the cylinder rod 10Y so that dust or the like does not enter into the rod-side oil chamber 40B.

The cylinder rod 10Y retracts when operating oil is supplied to the rod-side oil chamber 40B and the operating oil is discharged from the cab-side oil chamber 40A. Moreover, the cylinder rod 10Y extends when operating oil is discharged from the rod-side oil chamber 40B and the operating oil is supplied to the cab-side oil chamber 40A. That is, the cylinder rod 10Y moves linearly in the left-right direction in the figure.

A case 164 that covers the cylinder stroke sensor 16 and accommodates the cylinder stroke sensor 16 is provided outside the rod-side oil chamber 40B at the proximity of the cylinder head 10W. The case 164 is fixed to the cylinder head 10W by being fastened to the cylinder head 10W by bolts or the like.

The cylinder stroke sensor 16 includes a rotation roller 161, a rotation center shaft 162, and a rotation sensor portion 163. The rotation roller 161 has a surface in contact with the surface of the cylinder rod 10Y and is provided so as to rotate according to linear movement of the cylinder rod 10Y. That is, linear movement of the cylinder rod 10Y is converted into rotational movement by the rotation roller 161. The rotation center shaft 162 is disposed to be orthogonal to the direction of linear movement of the cylinder rod 10Y.

The rotation sensor portion 163 is configured to detect the amount of rotation (rotation angle) of the rotation roller 161 as an electrical signal. The electrical signal indicating the amount of rotation (rotation angle) of the rotation roller 161 detected by the rotation sensor portion 163 is output to the sensor controller 30 via an electrical signal line. The sensor controller 30 converts the electrical signal into the position (stroke position) of the cylinder rod 10Y of the boom cylinder 10.

As illustrated in FIG. 16, the rotation sensor portion 163 includes a magnet 163 a and a hall IC 163 b. The magnet 163 a which is a detecting medium is attached to the rotation roller 161 so as to rotate integrally with the rotation roller 161. The magnet 163 a rotates with rotation of the rotation roller 161 around the rotation center shaft 162. The magnet 163 a is configured such that the N pole and the S pole alternate according to the rotation angle of the rotation roller 161. The magnet 163 a is configured such that magnetic force (magnetic flux density) detected by the hall IC 163 b changes periodically every rotation of the rotation roller 161.

The hall IC 163 b is a magnetic force sensor that detects the magnetic force (magnetic flux density) generated by the magnet 163 a as an electrical signal. The hall IC 163 b is provided along the axial direction of the rotation center shaft 162 at a position separated by a predetermined distance from the magnet 163 a.

The electrical signal (phase shift pulse) detected by the hall IC 163 b is output to the sensor controller 30. The sensor controller 30 converts the electrical signal from the hall IC 163 b into an amount of rotation of the rotation roller 161 (that is, a displacement amount (boom cylinder length) of the cylinder rod 10Y of the boom cylinder 10).

Here, referring to FIG. 16, a relation between the rotation angle of the rotation roller 161 and the electrical signal (voltage) detected by the hall IC 163 b will be described. When the rotation roller 161 rotates and the magnet 163 a rotates with the rotation, the magnetic force (magnetic flux density) that passes through the hall IC 163 b changes periodically according to the rotation angle and the electrical signal (voltage) which is the sensor output changes periodically. The rotation angle of the rotation roller 161 can be measured from the magnitude of the voltage output from the hall IC 163 b.

Moreover, by counting the number of repetitions of each cycle of the electrical signal (voltage) output from the hall IC 163 b, it is possible to measure the number of rotations of the rotation roller 161. Moreover, the displacement amount (boom cylinder length) of the cylinder rod 10Y of the boom cylinder 10 is calculated based on the rotation angle of the rotation roller 161 and the number of rotations of the rotation roller 161.

Moreover, the sensor controller 30 can calculate the moving speed (cylinder speed) of the cylinder rod 10Y based on the rotation angle of the rotation roller 161 and the number of rotations of the rotation roller 161.

Hydraulic Cylinder

Next, the hydraulic cylinder according to the present embodiment will be described. The boom cylinder 10, the arm cylinder 11, and the bucket cylinder 12 are hydraulic cylinders. In the following description, the boom cylinder 10, the arm cylinder 11, and the bucket cylinder 12 will be appropriately collectively referred to as a hydraulic cylinder 60.

FIG. 17 is a schematic diagram illustrating an example of the control system 200 according to the present embodiment. FIG. 18 is an enlarged view of a portion of FIG. 17.

As illustrated in FIGS. 17 and 18, a hydraulic system 300 includes the hydraulic cylinder 60 including the boom cylinder 10, the arm cylinder 11, and the bucket cylinder 12 and a revolving motor 63 that allows the revolving structure 3 to revolve. The hydraulic cylinder 60 operates with operating oil supplied from a main hydraulic pump. The revolving motor 63 is a hydraulic motor and operates with operating oil supplied from a main hydraulic pump.

In the present embodiment, the direction control valve 64 that controls the direction in which operating oil flows is provided. The operating oil supplied from the main hydraulic pump is supplied to the hydraulic cylinder 60 via the direction control valve 64. The direction control valve 64 is a spool-type valve in which a rod-shaped spool is moved to change the flowing direction of operating oil. When the spool moves in an axial direction, the supply of operating oil to the cab-side oil chamber 40A (the oil passage 48) and the supply of operating oil to the rod-side oil chamber 40B (the oil passage 47) are switched. Moreover, when the spool moves in the axial direction, the amount (the amount of supply per unit time) of operating oil supplied to the hydraulic cylinder 60 is adjusted. When the amount of operating oil supplied to the hydraulic cylinder 60 is adjusted, the cylinder speed is adjusted.

A spool stroke sensor 65 that detects a moving distance (spool stroke) of the spool is provided in the direction control valve 64. Although not illustrated in the figure, the detection signal of the spool stroke sensor 65 is output to the work machine controller 26.

The driving of the direction control valve 64 is adjusted by the operating device 25. In the present embodiment, the operating device 25 is a pilot hydraulic-type operating device. Pilot oil which has been delivered from the main hydraulic pump and decompressed by the pressure-reducing valve is supplied to the operating device 25. Pilot oil which has been delivered from a pilot hydraulic pump different from the main hydraulic pump may be supplied to the operating device 25. The operating device 25 includes a pilot pressure adjustment valve. The pilot pressure is adjusted based on the amount of operation of the operating device 25. The direction control valve 64 is driven with the pilot pressure. When the pilot pressure is adjusted by the operating device 25, the movement amount and the moving speed of the spool in the axial direction are adjusted.

The direction control valve 64 is provided in each of the boom cylinder 10, the arm cylinder 11, the bucket cylinder 12, and the revolving motor 63. In the following description, the direction control valve 64 connected to the boom cylinder 10 will be appropriately referred to as a direction control valve 640. The direction control valve 64 connected to the arm cylinder 11 will be appropriately referred to as a direction control valve 641. The direction control valve 64 connected to the bucket cylinder 12 will be appropriately referred to as a direction control valve 642.

The operating device 25 and the direction control valve 64 are connected by the pilot pressure lines 450. In the present embodiment, the control valve 27, the pressure sensor 66, and the pressure sensor 67 are disposed in the pilot pressure lines 450.

In the following description, among the pilot pressure lines 450, a pilot pressure line 450 between the operating device 25 and the control valve 27 will be appropriately referred to as an oil passage 451, and a pilot pressure line 450 between the control valve 27 and the direction control valve 64 will be appropriately referred to as an oil passage 452.

The oil passage 451 includes an oil passage 451A that connects an oil passage 452A and the operating device 25 and an oil passage 451B that connects an oil passage 452B and the operating device 25. The oil passages 451A and 452A are connected to the direction control valve. The oil passage 452 is connected to the direction control valve 64. The pilot oil is supplied to the direction control valve 64 through the oil passage 452. The direction control valve 64 includes a first pressure receiving chamber and a second pressure receiving chamber. The oil passage 452 includes the oil passage 452A connected to the first pressure receiving chamber and the oil passage 452B connected to the second pressure receiving chamber.

When pilot oil is supplied to the first pressure receiving chamber of the direction control valve 64 through the oil passage 452A, the spool moves with the pilot pressure, and the operating oil is supplied to the rod-side oil chamber 40B via the direction control valve 64. The amount of operating oil supplied to the rod-side hydraulic chamber 40B is adjusted according to the amount of operation (spool movement amount) of the operating device 25.

When pilot oil is supplied to the second pressure receiving chamber of the direction control valve 64 through the oil passage 452B, the spool moves with the pilot pressure, and the operating oil is supplied to the cab-side oil chamber 40A via the direction control valve 64. The amount of operating oil supplied to the cab-side oil chamber 40A is adjusted according to the amount of operation (spool movement amount) of the operating device 25.

That is, when pilot oil of which the pilot pressure is adjusted by the operating device 25 is supplied to the direction control valve 64, the spool moves to one side in the axial direction. When pilot oil of which the pilot pressure is adjusted by the operating device 25 is supplied to the direction control valve 64, the spool moves to the other side in the axial direction. In this way, the position of the spool in the axial direction is adjusted.

In the following description, the oil passage 452A connected to the direction control valve 640 via which operating oil is supplied to the boom cylinder 10 will be appropriately referred to as an oil passage 4520A, and the oil passage 452B connected to the direction control valve 640 will be appropriately referred to as an oil passage 4520B. The oil passage 452A connected to the direction control valve 641 via which operating oil is supplied to the arm cylinder 11 will be appropriately referred to as an oil passage 4521A, and the oil passage 452B connected to the direction control valve 641 will be appropriately referred to as an oil passage 4521B. The oil passage 452A connected to the direction control valve 642 via which operating oil is supplied to the bucket cylinder 12 will be appropriately referred to as an oil passage 4522A, and the oil passage 452B connected to the direction control valve 642 will be appropriately referred to as an oil passage 4522B.

In the following description, the oil passage 451A connected to the oil passage 4520A will be appropriately referred to as an oil passage 4510A, and the oil passage 451B connected to the oil passage 4520B will be appropriately referred to as an oil passage 4510B. The oil passage 451A connected to the oil passage 4521A will be appropriately referred to as an oil passage 4511A, and the oil passage 451B connected to the oil passage 4521B will be appropriately referred to as an oil passage 4511B. The oil passage 451A connected to the oil passage 4522A will be appropriately referred to as an oil passage 4512A, and the oil passage 451B connected to the oil passage 4522B will be appropriately referred to as an oil passage 4512B.

As described above, according to the operation of the operating device 25, the boom 6 executes two operations of the lowering operation and the raising operation. When the operating device 25 is operated so that the raising operation of the boom 6 is executed, pilot oil is supplied to the direction control valve 640 connected to the boom cylinder 10 through the oil passages 4510B and 4520B. The direction control valve 640 operates based on pilot pressure. In this way, operating oil is supplied from the main hydraulic pump to the boom cylinder 10, and the boom cylinder 10 is extended. The raising operation of the boom 6 is executed according to extension of the boom cylinder. When the operating device 25 is operated so that the lowering operation of the boom 6 is executed, pilot oil is supplied to the direction control valve 640 connected to the boom cylinder 10 through the oil passages 4510A and 4520A. The direction control valve 640 operates based on pilot pressure. In this way, operating oil is supplied from the main hydraulic pump to the boom cylinder 10, and the boom cylinder 10 is retracted. The lowering operation of the boom 6 is executed according to retraction of the boom cylinder.

Moreover, according to the operation of the operating device 25, the arm 7 executes two operations of the lowering operation and the raising operation. When the operating device 25 is operated so that the lowering operation of the arm 7 is executed, pilot oil is supplied to the direction control valve 641 connected to the arm cylinder 11 through the oil passages 4511B and 4521B. The direction control valve 641 operates based on pilot pressure. In this way, operating oil is supplied from the main hydraulic pump to the arm cylinder 11, and the arm cylinder 11 is extended. The lowering operation of the arm 7 is executed according to extension of the arm cylinder 11. When the operating device 25 is operated so that the raising operation of the arm 7 is executed, pilot oil is supplied to the direction control valve 641 connected to the arm cylinder 11 through the oil passages 4511A and 4521A. The direction control valve 641 operates based on pilot pressure. In this way, operating oil is supplied from the main hydraulic pump to the arm cylinder 11, and the arm cylinder 11 is retracted. The raising operation of the arm 7 is executed according to retraction of the arm cylinder 11.

Moreover, according to the operation of the operating device 25, the bucket 8 executes two operations of the lowering operation and the raising operation. When the operating device 25 is operated so that the lowering operation of the bucket 8 is executed, pilot oil is supplied to the direction control valve 642 connected to the bucket cylinder 12 through the oil passages 4512B and 4522B. The direction control valve 642 operates based on pilot pressure. In this way, operating oil is supplied from the main hydraulic pump to the bucket cylinder 12, and the bucket cylinder 12 is extended. The lowering operation of the bucket 8 is executed according to extension of the bucket cylinder 12. When the operating device 25 is operated so that the raising operation of the bucket 8 is executed, pilot oil is supplied to the direction control valve 642 connected to the bucket cylinder 12 through the oil passages 4512A and 4522A. The direction control valve 642 operates based on pilot pressure. In this way, operating oil is supplied from the main hydraulic pump to the bucket cylinder 12, and the bucket cylinder 12 is retracted. The raising operation of the bucket 8 is executed according to retraction of the bucket cylinder 12.

Moreover, according to the operation of the operating device 25, the revolving structure 3 executes two operations of the right revolving operation and the left revolving operation. When the operating device 25 is operated so that the right revolving operation of the revolving structure 3 is executed, operating oil is supplied to the revolving motor 63. When the operating device 25 is operated so that the left revolving operation of the revolving structure 3 is executed, the operating oil is supplied to the revolving motor 63.

The control valve 27 adjusts pilot pressure based on a control signal (EPC current) from the work machine controller 26. The control valve 27 is an electromagnetic proportional control valve and is controlled based on a control signal from the work machine controller 26. The control valve 27 includes a control valve 27A that can adjust the pilot pressure of pilot oil supplied to the first pressure receiving chamber of the direction control valve 64 to adjust the amount of operating oil supplied to the rod-side oil chamber 40B via the direction control valve 64 and a control valve 27B that can adjust the pilot pressure of pilot oil supplied to the second pressure receiving chamber of the direction control valve 64 to adjust the amount of operating oil supplied to the cab-side oil chamber 40A via the direction control valve 64.

The pressure sensors 66 and 67 that detect the pilot pressure are provided on both sides of the control valve 27. In the present embodiment, the pressure sensor 66 is disposed in the oil passage 451 between the operating device 25 and the control valve 27. The pressure sensor 67 is disposed in the oil passage 452 between the control valve 27 and the direction control valve 64. The pressure sensor 66 can detect the pilot pressure before being adjusted by the control valve 27. The pressure sensor 67 can detect the pilot pressure adjusted by the control valve 27. Although not illustrated in the figure, the detection results of the pressure sensors 66 and 67 are output to the work machine controller 26.

In the following description, the control valves 27 capable of adjusting the pilot pressure of pilot oil to the direction control valve 640 via which operating oil is supplied to the boom cylinder 10 will be appropriately referred to as control valves 270. Moreover, among the control valves 270, one set of control valves (corresponding to control valves 27A) will be appropriately referred to as control valves 270A, and the other set of control valves (corresponding to control valves 27B) will be appropriately referred to as control valves 270B. The control valves 27 capable of adjusting the pilot pressure of pilot oil to the direction control valve 641 via which operating oil is supplied to the arm cylinder 11 will be appropriately referred to as control valves 271. Moreover, among the control valves 271, one set of control valves (corresponding to control valves 27A) will be appropriately referred to as control valves 271A, and the other set of control valves (corresponding to control valves 27B) will be appropriately referred to as control valves 271B. The control valves 27 capable of adjusting the pilot pressure of pilot oil to the direction control valve 642 via which operating oil is supplied to the bucket cylinder 12 will be appropriately referred to as control valves 272. Moreover, among the control valves 272, one set of control valves (corresponding to control valves 27A) will be appropriately referred to as control valves 272A, and the other set of control valves (corresponding to control valves 27B) will be appropriately referred to as control valves 272B.

In the following description, the pressure sensor 66 that detects the pilot pressure of the oil passage 451 connected to the direction control valve 640 via which operating oil is supplied to the boom cylinder 10 will be appropriately referred to as a pressure sensor 660, and the pressure sensor 67 that detects the pilot pressure of the oil passage 452 connected to the direction control valve 640 will be appropriately referred to as a pressure sensor 670. Moreover, the pressure sensor 660 disposed in the oil passage 4510A will be appropriately referred to as a pressure sensor 660A, and the pressure sensor 660 disposed in the oil passage 4510B will be appropriately referred to as a pressure sensor 660B. Moreover, the pressure sensor 670 disposed in the oil passage 4520A will be appropriately referred to as a pressure sensor 670A, and the pressure sensor 670 disposed in the oil passage 4520B will be appropriately referred to as a pressure sensor 670B.

In the following description, the pressure sensor 66 that detects the pilot pressure of the oil passage 451 connected to the direction control valve 641 via which operating oil is supplied to the arm cylinder 11 will be appropriately referred to as a pressure sensor 661, and the pressure sensor 67 that detects the pilot pressure of the oil passage 452 connected to the direction control valve 641 will be appropriately referred to as a pressure sensor 671. Moreover, the pressure sensor 661 disposed in the oil passage 4511A will be appropriately referred to as a pressure sensor 661A, and the pressure sensor 661 disposed in the oil passage 4511B will be appropriately referred to as a pressure sensor 661B. Moreover, the pressure sensor 671 disposed in the oil passage 4521A will be appropriately referred to as a pressure sensor 671A, and the pressure sensor 671 disposed in the oil passage 4521B will be appropriately referred to as a pressure sensor 671B.

In the following description, the pressure sensor 66 that detects the pilot pressure of the oil passage 451 connected to the direction control valve 642 via which operating oil is supplied to the bucket cylinder 12 will be appropriately referred to as a pressure sensor 662, and the pressure sensor 67 that detects the pilot pressure of the oil passage 452 connected to the direction control valve 642 will be appropriately referred to as a pressure sensor 672. Moreover, the pressure sensor 661 disposed in the oil passage 4512A will be appropriately referred to as a pressure sensor 661A, and the pressure sensor 661 disposed in the oil passage 4512B will be appropriately referred to as a pressure sensor 661B. Moreover, the pressure sensor 672 disposed in the oil passage 4522A will be appropriately referred to as a pressure sensor 672A, and the pressure sensor 672 disposed in the oil passage 4522B will be appropriately referred to as a pressure sensor 672B.

When limited excavation control is not performed and the operation of each work machine is not limited, the work machine controller 26 controls the control valve 27 to open the pilot pressure line 450. When the pilot pressure line 450 is open, the pilot pressure of the oil passage 451 becomes the same as the pilot pressure of the oil passage 452. In the open state of the pilot pressure line 450, the pilot pressure is adjusted based on the amount of operation of the operating device 25.

When limited excavation control is performed and the work machine 2 is controlled by the work machine controller 26, the work machine controller 26 outputs a control signal to the control valve 27. The oil passage 451 has a predetermined pressure due to the action of a pilot relief valve, for example. When the control signal is output from the work machine controller 26 to the control valve 27, the control valve 27 operates based on the control signal. The operating oil of the oil passage 451 is supplied to the oil passage 452 via the control valve 27. The pressure of the operating oil of the oil passage 452 is adjusted (reduced) by the control valve 27. The pressure of the operating oil of the oil passage 452 acts on the direction control valve 64. As a result, the direction control valve 64 operates based on the pilot pressure controlled by the control valve 27. In the present embodiment, the pressure sensor 66 detects the pilot pressure before being adjusted by the control valve 27. The pressure sensor 67 detects the pilot pressure after being adjusted by the control valve 27.

When the operating oil of which the pressure is adjusted by the control valve 27A is supplied to the direction control valve 64, the spool moves to one side in the axial direction. When the operating oil of which the pressure is adjusted by the control valve 27B is supplied to the direction control valve 64, the spool moves to the other side in the axial direction. In this way, the position of the spool in the axial direction is adjusted.

For example, the work machine controller 26 can adjust the pilot pressure to the direction control valve 640 connected to the boom cylinder 10 by outputting a control signal to at least one of the control valves 270A and 270B.

Moreover, the work machine controller 26 can adjust the pilot pressure to the direction control valve 641 connected to the arm cylinder 11 by outputting a control signal to at least one of the control valves 271A and 271B.

Moreover, the work machine controller 26 can adjust the pilot pressure to the direction control valve 642 connected to the bucket cylinder 12 by outputting a control signal to at least one of the control valves 272A and 272B.

The work machine controller 26 limits the speed of the boom 6 based on the target excavation landform U indicating the designed landform which is a target shape of an excavation object and the bucket position data (cutting edge position data S) indicating the position of the bucket 8 so that a speed at which the bucket 8 approaches the target excavation landform U decreases according to the distance d between the target excavation landform U and the bucket 8. The work machine controller 26 includes a boom intervention unit that outputs a control signal for limiting the speed of the boom 6. In the present embodiment, when the work machine 2 is driven based on the operation of the operating device 25, the movement of the boom 6 is controlled (intervened) based on the control signal output from the boom intervention unit of the work machine controller 26 so that the cutting edge 8 a of the bucket 8 does not dig into the target excavation landform U. When the bucket 8 performs excavation, the raising operation of the boom 6 is executed by the work machine controller 26 so that the cutting edge 8 a does not dig into the target excavation landform U.

In the present embodiment, the oil passage 502 is connected to the control valve 27C that operates based on an intervention control signal output from the work machine controller 26 in order to perform intervention control. The oil passage 501 is connected to the control valve 27C so as to supply pilot oil to the direction control valve 640 connected to the boom cylinder 10. The oil passage 502 is connected to the control valve 27C and the shuttle valve 51 and is connected to the oil passage 4520B connected to the direction control valve 640 via the shuttle valve 51.

The shuttle valve 51 has two inlet ports and one outlet port. One inlet port is connected to the oil passage 502. The other inlet port is connected to the oil passage 4510B. The outlet port is connected to the oil passage 4520B. The shuttle valve 51 connects an oil passage having a higher pilot pressure among the oil passages 502 and 4510B to the oil passage 4520B. For example, when the pilot pressure of the oil passage 502 is higher than the pilot pressure of the oil passage 4510B, the shuttle valve 51 operates so that the oil passages 502 and 4520B are connected and the oil passages 4510B and 4520B are not connected. In this way, the pilot oil of the oil passage 502 is supplied to the oil passage 4520B via the shuttle valve 51. When the pilot pressure of the oil passage 4510B is higher than the pilot pressure of the oil passage 502, the shuttle valve 51 operates so that the oil passages 4510B and 4520B are connected and the oil passages 502 and 4520B are not connected. In this way, the pilot oil of the oil passage 4510B is supplied to the oil passage 4520B via the shuttle valve 51.

A pressure sensor 68 that detects the pilot pressure of the pilot oil of the oil passage 501 is provided in the oil passage 501. The pilot oil before passing through the control valve 27C flows in the oil passage 501. The pilot oil having passed through the control valve 27C flows in the oil passage 502. The control valve 27C is controlled based on the control signal output from the work machine controller 26 in order to execute intervention control.

When intervention control is not executed, the work machine controller 26 does not output a control signal to the control valve 27 so that the direction control valve 64 is driven based on the pilot pressure adjusted by the operation of the operating device 25. For example, the work machine controller 26 opens the control valve 270B to its full width and closes the control valve 27C and the oil passage 501 so that the direction control valve 640 is driven based on the pilot pressure adjusted by the operation of the operating device 25.

When intervention control is executed, the work machine controller 26 controls the respective control valves 27 so that the direction control valve 64 is driven based on the pilot pressure adjusted by the control valve 27C. For example, when intervention control of limiting the movement of the boom 6 is executed, the work machine controller 26 controls the control valve 27C so that the pilot pressure adjusted by the control valve 27C is higher than the pilot pressure adjusted by the operating device 25. In this way, the pilot oil from the control valve 27C is supplied to the direction control valve 640 via the shuttle valve 51.

When the boom 6 is raised at a high speed by the operating device 25 so that the bucket 8 does not dig into the target excavation landform U, the intervention control is not executed. When the operating device 25 is operated so that the boom 6 is raised at a high speed and the pilot pressure is adjusted based on the amount of operation, the pilot pressure adjusted by the operation of the operating device 25 becomes higher than the pilot pressure adjusted by the control valve 27C. In this way, the pilot oil having the pilot pressure adjusted by the operation of the operating device 25 is supplied to the direction control valve 640 via the shuttle valve 51.

Here, when the work machine controller 26 determines that it is necessary to limit the excavation of the arm 7, the work machine controller 26 outputs a command so that the amount of oil supplied to the control valve 271B decreases. In this way, the supply of pilot pressure to the oil passage 4521B according to the lever operation on the arm cylinder 11 is limited.

Control of Arm First Embodiment

FIG. 19 is a diagram schematically illustrating an example of the operation of the work machine 2 when limited excavation control (boom intervention control) is performed.

As described above, the hydraulic system 300 includes the boom cylinder 10 for driving the boom 6, the arm cylinder 11 for driving the arm 7, and the bucket cylinder 12 for driving the bucket 8.

As illustrated in FIG. 19, during the excavation operation of the bucket 8, the hydraulic system 300 operates so that the boom 6 is raised and the arm 7 is lowered. In the excavation operation, intervention control including the raising operation of the boom 6 is executed so that the bucket 8 does not dig into the target excavation landform U.

In the boom intervention control, there is a possibility that the boom 6 is not moved at a high speed but is moved slower than the movement of the arm 7 and the bucket 8. In the excavation operation, since the arm 7 is lowered, the arm 7 can move at a higher speed than the boom 6 due to the action of gravity (its own weight). With the intervention control on the boom 6, the boom 6 is raised.

Moreover, load corresponding to the weight of the arm 7 and weight of the bucket 8 is applied to the arm cylinder 11, whereas load corresponding to the weight of the boom 6, the weight of the arm 7, and the weight of the bucket 8 is applied to the boom cylinder 10. That is, the load applied to the boom cylinder 10 is larger than the weight applied to the arm cylinder 11. The boom cylinder 10 needs to operate while resisting against the load. As a result, it may be difficult for the boom 6 to be moved appropriately (raised) in synchronization with the movement of the arm 7 so that the bucket 8 is suppressed from digging into the target excavation landform U. Moreover, the boom 6 is driven by the hydraulic cylinder (the boom cylinder) 10. Due to this, it may be difficult for the boom 6 to satisfactorily follow the movement of the arm 7. As a result, the bucket 8 may dig into the target excavation landform U and the excavation accuracy may decrease.

In the present embodiment, in the boom intervention control including the raising operation of the boom 6, the work machine controller 26 performs limitation control on the arm 7 so that the arm 7 moves in synchronization with the movement of the boom 6 by taking a difference in the operating conditions (raising operation or lowering operation) of the boom 6 and the arm 7 and a difference in the load conditions of the boom cylinder 10 and the arm cylinder 11 during the excavation operation into consideration.

FIG. 20 is a functional block diagram illustrating an example of the control system 200 according to the present embodiment. As illustrated in FIG. 20, the control system 200 includes the operating device 25 operated in order to drive the arm 7, a detection device 70 that detects the amount of operation MA (hereinafter simply M) of the operating device 25, and the work machine controller 26. The work machine controller 26 includes a timer 261 that starts time measurement based on the detection result of the detection device 70, a limit value setting unit 262 that sets a limited amount of operation Mr for limiting the speed of the arm 7 in association with the time elapsed from the start time of the time measurement of the timer 261, the arm control unit 263 that generates a control signal N so that the arm 7 is driven with the limited amount of operation Mr in a predetermined period from the start of the time measurement of the timer 261 and outputs an arm speed limit Vc_am_lmt based on the control signal N, and the storage unit 264.

In the present embodiment, the detection device 70 includes the pressure sensor 66 (661B). The detection device 70 detects the amount of operation M of the operating device 25 by detecting the pilot pressure adjusted by the operating device 25.

When the operating device 25 is operated at a high speed (abruptly) by the operator in order to lower the arm 7, the work machine controller 26 limits the amount of operation (amount of arm operation) M of the operating device 25 and drives the arm 7 with the limited amount of operation Mr so that a delay in the raising intervention speed of the boom 6 in relation to the lowering speed of the arm 7 does not occur. That is, in the present embodiment, in the boom intervention control, the arm 7 is driven with the limited amount of operation Mr in at least a portion of the period where the boom 6 is raised and the arm 7 is lowered. Due to this, even when the operating device 25 is operated at a high speed by the operator in order to drive the arm 7, since the arm 7 moves at a limited speed (low speed), the occurrence of a following delay of the boom 6 in which the raising intervention speed of the boom 6 is delayed in relation the lowering speed of the arm 7 is suppressed.

The limited amount of operation Mr is a value that can suppress a following delay of the boom 6 even when the arm 7 is operated with the limited amount of operation Mr. The limited amount of operation Mr is obtained in advance through experiments or simulations and is stored in a memory (storage unit) of the work machine controller 26.

In the present embodiment, the work machine controller 26 compares the amount of arm operation M detected by the detection device 70 with the limited amount of operation Mr. The amount of arm operation M detected by the detection device 70 and the limited amount of operation Mr from the limit value setting unit 262 are output to the arm control unit 263. The arm control unit 263 includes a comparing unit. The comparing unit of the arm control unit 263 compares the amount of arm operation M with the limited amount of operation Mr.

The arm control unit 263 selects the smaller amount of operation among the amount of arm operation M and the limited amount of operation Mr based on a comparison result between the amount of arm operation M and the limited amount of operation Mr. The arm control unit 263 outputs an arm speed limit Vc_am_lmt to the work machine control unit 57 so that the arm 7 is driven with the selected amount of operation among the amount of arm operation M and the limited amount of operation Mr.

In the following description, control of limiting the operation (speed) of the arm 7 so that a delay in the raising intervention speed of the boom 6 in relation to the lowering speed of the arm 7 does not occur will be appropriately referred to as arm speed limitation control.

Moreover, the selected amount of operation (the smaller amount of operation) among the amount of arm operation M and the limited amount of operation Mr will be appropriately referred to as an amount of operation Mf.

FIG. 21 is a flowchart for describing an example of the operation of the control system 200 according to the present embodiment. FIGS. 22, 23, and 24 are timing charts for describing an example of the operation of the control system 200 according to the present embodiment.

In the excavation operation, the operating device 25 is operated by the operator (step SB1). The operator operates the operating device 25 in order to drive the arm 7. The operating device 25 is operated so that the arm 7 is lowered.

Intervention control on the boom 6 starts so that the bucket 8 does not dig into the target excavation landform U (step SB2). In the intervention control, the speed of the boom 8 is limited based on the target excavation landform U indicating the target shape of an excavation object and the cutting edge position data S indicating the position of the cutting edge 8 a of the bucket 8 so that the speed at which the bucket 8 approaches the target excavation landform U decreases according to the distance d between the target excavation landform U and the bucket 8. The intervention control includes the raising operation of the boom 6. With the intervention control on the boom 6, the boom 6 is raised.

The amount of operation M of the operating device 25 is detected by the detection device 70 (step SB3). The detection device 70 includes the pressure sensor 66 and detects the amount of operation M of the operating device 25 by detecting the pilot pressure adjusted by the operating device 25. In the present embodiment, at least the pilot pressure (the pilot pressure of the oil passage 451) to the direction control valve 641 is detected by the pressure sensor 661.

The detection value of the detection device 70 (the pressure sensor 661) is output to the timer 261. The timer 261 starts time measurement based on the detection result of the detection device 70 (step SB4). In FIGS. 22, 23, and 24, time t0 is the start time of the time measurement of the timer 261.

In FIG. 20 of the present embodiment, the timer 261 starts the time measurement when the operating device 25 starts operating in order to drive the arm 7. That is, time t0 is the start time of the operation of the operating device 25. The start time of the time measurement of the timer 261 may be the time at which the detection value of the detection device 70 exceeds a threshold value. The threshold value may be the value of the limited amount of operation Mr. The start time of the time measurement of the timer 261 may be the time at which the amount (change rate) of increase per unit time of the detection value of the detection device 70 exceeds an allowable value.

The limit value setting unit 262 sets the limited amount of operation Mr for limiting the speed (lowering speed) of the arm 7 in association with the time elapsed from the start time t0 of the time measurement of the timer 261 (step SB5). The limited amount of operation Mr is a value that can suppress the occurrence of a following delay of the boom 6 even when the arm 7 is operated with the limited amount of operation Mr. The limited amount of operation Mr is obtained in advance through experiments or simulations. The limited amount of operation Mr is set in association with the time elapsed from the start time t0 of the time measurement of the timer 261. In the following description, data indicating the limited amount of operation Mr set in association with time will be appropriately referred to as a limit pattern.

FIG. 22 illustrates a relation between the time elapsed from the start time t0 and the amount of operation

M of the arm 7 by the operating device 25. FIG. 23 illustrates a relation between the time elapsed from the start time t0 and the limited amount of operation Mr set by the limit value setting unit 262. That is, FIG. 23 illustrates a limit pattern. FIG. 24 illustrates a relation between the time elapsed from the start time t0 and the amount of operation Mf of the arm 7. As described above, the start time t0 is the start time of the time measurement of the timer 261. In FIGS. 22, 23, and 24, the horizontal axis is time (elapsed time). In FIG. 22, the vertical axis is the amount of operation M of the arm 7 and the count value of the timer 261. In FIG. 23, the vertical axis is the limited amount of operation Mr and the count value of the timer 261. In FIG. 24, the vertical axis is the amount of operation Mf of the arm 7 and the count value of the timer 261.

In FIG. 22, the relation between the time elapsed from the start time t0 and the amount of operation M of the arm 7 by the operating device 25 is indicated by line S1. In FIG. 23, the relation (limit pattern) between the time elapsed from the start time t0 and the limited amount of operation Mr is indicated by line S2. In FIG. 24, the relation (limit pattern) between the time elapsed from the start time t0 and the amount of operation Mf is indicated by line Sc. Line Lt indicates the count value of the timer 261. In FIG. 23, the line S2 is depicted by a solid line and the line S1 is depicted by a dot line.

In the present embodiment, the amounts of operation (M, Mr, and Mf) of the arm 7 are associated with the pilot pressure acting on the direction control valve 641 connected to the arm cylinder 11. In the present embodiment, the unit of the amounts of operation (M, Mr, and Mf) of the arm 7 is mega Pascal (MPa). The pilot pressure corresponding to the amount of operation M is adjusted by the operating device 25. The pilot pressure corresponding to the limited amount of operation Mr is adjusted by the control valve 271 that is controlled by the arm control unit 263.

The amount of operation M corresponds to the detection value of the pressure sensor 661 that detects the pilot pressure acting on the direction control valve 640 connected to the arm cylinder 11. The pressure sensor 661 outputs the detection value of the pilot pressure corresponding to the amount of operation M of the operating device 25 for driving the arm cylinder 11.

The limited amount of operation Mr corresponds to a target value (limit value) of the pilot pressure acting on the direction control valve 640 connected to the arm cylinder 11. The correlation between the pilot pressure and the limited amount of operation Mr is obtained in advance and is stored in the storage unit 264 of the work machine controller 26. During the arm speed limitation control, the arm control unit 263 determines the limited amount of operation Mr so that the target pilot pressure acts on the direction control valve 641 and generates a control signal N so that the pilot pressure corresponding to the limited amount of operation Mr is obtained.

The amount of operation Mf corresponds to the detection value of the pressure sensor 671 that detects the pilot pressure acting on the direction control valve 640 connected to the arm cylinder 11. As described above, the amount of operation Mf is the smaller amount of operation among the amount of operation M and the limited amount of operation Mr. When the amount of operation M is smaller than the limited amount of operation Mr, the arm control unit 263 does not generate the control signal N. When the amount of operation M is smaller than the limited amount of operation Mr, the control valve 271 is open to its full width and the pilot pressure based on the amount of operation M acts on the direction control valve 641. When the amount of operation M is larger than the limited amount of operation Mr, the arm control unit 263 generates the control signal N to the control valve 271 so that the arm speed limitation control is executed based on the limited amount of operation Mr. When the amount of operation M is larger than the limited amount of operation Mr, the pilot pressure based on the limited amount of operation Mr, adjusted by the control valve 271 acts on the direction control valve 641.

FIG. 22 illustrates an example of the profile of the amount of operation M. The profile of the amount of operation M is indicated by line Si. As illustrated in FIG. 22, at time t0, the operating device 25 is operated by the operator in order to drive the arm 7. The timer 261 starts time measurement. In the present embodiment, as an example, as indicated by the line S1 of FIG. 22, a case where the operating device 25 is operated by the operator so that the amount of operation M increases abruptly from 0 to value M3 will be considered. The amount of operation M maintains the value M3 for a certain period after reaching the value M3 and then decreases until it reaches 0. When the arm speed limitation control is not executed, the amount of operation M (Mf) has a profile indicated by the line S1 of FIG. 22. In this case, a delay in the raising intervention speed of the boom 6 in relation to the lowering speed of the arm 7 may occur.

FIG. 23 illustrates an example of the profile of the limited amount of operation Mr. The profile of the limited amount of operation Mr is indicated by line S2. As described above, the limited amount of operation Mr is an amount of operation that is determined in advance so that a delay in the raising intervention speed of the boom 6 does not occur. Here, when the amount of operation M exceeds a value M1, the value M1 is set as a lower limit threshold value so that the limited amount of operation Mr is generated. The limited amount of operation Mr is smaller than the amount of operation M. In the present embodiment, in a predetermined period Ts where the time measurement is performed by the timer 261, the driving of the arm 7 is controlled so that the arm 7 is not operated with the amount of operation M larger than the limited amount of operation Mr. In the present embodiment, the predetermined period Ts is a period between the time t0 and the time t1.

As illustrated in FIG. 23, since the amount of operation M exceeds the value M1 at the time t0 at which the operator performs operations, the limited amount of operation Mr increases up to a value M2 from 0. That is, in a period near the start time t0, the limited amount of operation Mr has the value M2. The value M2 is smaller than a value M3. The limited amount of operation Mr maintains the value M2 for a certain period after reaching the value M2, and increases gradually and reaches the value M3 at the ending time t1. After that, the limited amount of operation Mr decreases until it reaches 0 at the time at which the amount of operation M based on the operation of the operator is smaller than the value M1 after maintaining the value M3. In this manner, in the predetermined period Ts between the time t0 and the time t1, the limited amount of operation Mr is set to be smaller than the amount of operation M. The value at the time t0 which is the starting point of the limit pattern S2 illustrated in FIG. 23 is M2 and the value at the time t1 which is the ending point of the limit pattern S2 is M3. In the period later than the time t1, the limited amount of operation Mr is the same as the amount of operation M. In this manner, in the present embodiment, the limited amount of operation Mr in the first half of the predetermined period Ts is smaller than the limited amount of operation Mr in the second half of the predetermined period Ts.

In the present embodiment, the arm control unit 263 compares the amount of operation M with the limited amount of operation Mr, selects the smaller amount of operation, and generates the control signal N based on the selected amount of operation Mf. In the present embodiment, as described with reference to FIGS. 22 and 23, in the predetermined period Ts between the time t0 and the time t1, the limited amount of operation Mr is smaller than the amount of operation M. Thus, in the predetermined period between the time t0 and the time t1, the arm control unit 263 generates the control signal N so that the arm 7 is driven based on the limited amount of operation Mr.

In the period later than the time t1, the limited amount of operation Mr is set to the value M3. In the present embodiment, in the period later than the time t1, the limited amount of operation Mr is the same as the amount of operation M. In the present embodiment, the arm control unit 263 compares the amount of operation M with the limited amount of operation Mr and selects the amount of operation M. In the present embodiment, at the time t1, the arm speed limitation control ends. That is, in the present embodiment, the driving (arm speed limitation control) of the arm 7 based on the limited amount of operation Mr starts at the start time t0 of the time measurement of the timer 261 and ends at the ending time t1 after the elapse of the predetermined period Ts from the start time t0. After the elapse of the predetermined period Ts from the start time t0 of the time measurement of the timer 261, the driving based on the limited amount of operation Mr is disabled.

FIG. 24 illustrates an example of the profile of the amount of operation Mf. The profile of the amount of operation Mf is indicated by the line Sc. As illustrated in FIG. 24, in the predetermined period Ts between the time t0 and the time t1, the arm 7 is operated with the pilot pressure adjusted according to the limited amount of operation Mr as indicated by the line Sc. After the elapse of the predetermined period Ts, the arm 7 is operated with the pilot pressure adjusted according to the amount of operation M as indicated by the line Sc.

That is, in the present embodiment, the profile of the amount of operation Mf of the arm 7 is determined so as to change along the line Sc of FIG. 24. Specifically, the operation of the operating device 25 starts at the time t0, and the amount of operation Mf increases abruptly from 0 to the value M2 and maintains the value M2 for a certain period. After that, the amount of operation Mf increases gradually and reaches the value M3 at the time t1. The amount of operation Mf maintains the value M3 for a certain period after the time t1 and then decreases to 0.

The arm control unit 263 generates the control signal N so that the arm 7 is driven with the limited amount of operation Mr in the predetermined period Ts from the start time t0 of the time measurement of the timer 261 (step SB6). That is, the arm control unit 263 generates the control signal N for driving the arm 7 so that the arm 7 is driven according to the profile of the limited amount of operation Mr in the predetermined period Ts.

The arm control unit 263 generates the control signal N so that the arm 7 is driven with the limited amount of operation Mr in the predetermined period Ts and stops generating the control signal N so that the arm 7 is driven with the amount of operation M after the elapse of the predetermined period Ts where the driving based on the limited amount of operation Mr is disabled. That is, the arm control unit 263 generates the control signal N so that the arm 7 moves at a low speed in the predetermined period Ts and the arm 7 moves at a high speed after the elapse of the predetermined period Ts.

The arm speed limit Vc_am_lmt is output based on the control signal N generated by the arm control unit 263, and the arm operation command CA based on the arm speed limit Vc_am_lmt is output to the control valve 27 connected to the arm cylinder 11. The control valve 27 adjusts (limits) the pilot pressure based on the control signal N so that the amount of operating oil supplied to the arm cylinder 11 is adjusted (limited). When the amount of operating oil supplied to the arm cylinder 11 is limited, the cylinder speed is adjusted and the speed of the arm 7 is limited. The arm control unit 263 suppresses the speed (lowering speed) of the arm 7 in the lowering operation of the arm 7. In the present embodiment, although the speed of the arm 7 is limited in the predetermined period Ts, it is possible to suppress a decrease in the excavation accuracy even when the predetermined period Ts is not provided.

[Effects]

As described above, according to the present embodiment, since the speed of the arm 7 is limited in the intervention control (limited excavation control) of the boom 6, a delay in the raising intervention speed of the boom 6 in relation to the excavation operation of the arm 7 is suppressed. Thus, a decrease in the excavation accuracy is suppressed.

Further, in the present embodiment, the timer 261 performs time measurement, and the driving of the arm 7 is limited for the predetermined period Ts only from the start time t0 of the time measurement of the timer 261. Due to this, a decrease in the excavation accuracy is suppressed without complicating the control. Moreover, since the arm 7 is driven based on the operation of the operator after the elapse of the predetermined period Ts, a decrease in the workability is suppressed.

In the present embodiment, the start time (the start time of limiting the driving of the arm 7) t0 of the time measurement of the timer 261 includes at least one of a start time of the operation of the operating device 25, the time at which the detection value of the detection device 70 exceeds the threshold value, and the time at which the amount of increase per unit time of the detection value of the detection device 70 exceeds an allowable value. In this way, it is possible to smoothly limit the driving of the arm 7 in a period where a delay in the raising intervention speed of the boom 6 in relation to the excavation operation of the arm 7 is likely to occur.

In the present embodiment, the driving based on the limited amount of operation Mr is disabled after the elapse of the predetermined period Ts from the start time t0 of the time measurement of the timer 261. In this way, it is possible to perform a normal operation based on the amount of arm operation M of the operating device 25.

In the present embodiment, the limited amount of operation Mr in the first half of the predetermined period Ts is smaller than the limited amount of operation Mr in the second half. In the first half of the predetermined period Ts, the limitation on the arm 7 is strengthened, whereby the occurrence of a following delay of the boom 6 is suppressed. In the second half of the predetermined period Ts, the limitation on the arm 7 is weakened, whereby a decrease in the operation efficiency is suppressed.

In the present embodiment, the arm 7 is driven with the limited amount of operation Mr in at least a portion of the period where the boom 6 is raised and the arm 7 is lowered. Due to this, even when the operating device 25 is operated at a high speed by the operator in order to drive the arm 7, since the arm 7 moves at a limited speed (low speed), a delay in the raising intervention speed of the boom 6 in relation the excavation operation of the arm 7 is suppressed.

In the present embodiment, in the arm speed limitation control, it is possible to adjust the pilot pressure according to the control signal N to accurately adjust the amount of operating oil supplied to the arm cylinder 11 at a high speed.

In the present embodiment, in the boom intervention control, the movement of the arm 7 is limited in order to suppress a following delay of the boom 6. In the boom intervention control, the movement of the bucket 8 may be limited. That is, in the above-described embodiment, the operating device 25 may be operated in order to drive the bucket 8, an amount of operation of the operating device 25 may be detected by the detection device 70 (the pressure sensor 662), the time measurement of the timer 261 may start based on the detection result of the detection device 70, the limited amount of operation for limiting the speed of the bucket 8 may be set in association with the time elapsed from the start time of the time measurement of the timer 261, a bucket control unit may be provided so that the bucket 8 is driven with a limited control amount in a predetermined period from the start time of the time measurement of the timer 261, and a control signal may be output from the bucket control unit. The same is true for the following embodiments.

In the intervention control, the movement of both the arm 7 and the bucket 8 may be limited. The same is true for the following embodiments.

Control of Arm Second Embodiment

Next, a second embodiment of control of the arm 7 (or the bucket 8) will be described. In the following description, the same or equivalent portions as those of the above-described embodiment will be denoted by the same reference numerals, and description thereof will be simplified or omitted.

FIG. 25 is a schematic diagram illustrating an example of a control system 200 according to the present embodiment. FIGS. 26, 27, and 28 are timing charts for describing an example of the operation of the control system 200 according to the present embodiment.

As illustrated in FIG. 25, the control system 200 includes a variable capacitance hydraulic pump (main hydraulic pump) 41 that supplies operating oil, a direction control valve 641 (64) to which the operating oil from the hydraulic pump 41 is supplied, an arm cylinder 11 that is driven with the operating oil supplied from the hydraulic pump 41 via the direction control valve 641, a pump controller (pump control unit) 49 that controls the hydraulic pump 41, a mode setting unit 26M, and a work machine controller 26. The pump controller 49 is connected to the work machine controller 26. The pump controller 49 outputs a control signal to a pump swash plate control device 41C to control a pump swash plate of the hydraulic pump 41.

The work machine controller 26 is connected to a man machine interface 32. The man machine interface 32 includes the mode setting unit 26M. The mode setting unit 26M sets an operation mode of the excavator 100 based on the operation of the operator. In the present embodiment, the mode setting unit 26M stores information on a first operation mode and information on a second operation mode. The mode setting unit may be provided with a switch or the like separately.

In the present embodiment, the control system 200 controls the excavator 100 in the first and second operation modes. The first operation mode is an operation efficiency priority mode (P-mode). The second operation mode is a fuel-saving mode (economy mode). In the second operation mode, the supply of operating oil is limited so that a largest discharge capacity of operating oil from the hydraulic pump 41, which is a second largest discharge capacity, is smaller than a largest discharge capacity of operating oil from the hydraulic pump 41 which is a first largest discharge capacity in the first operation mode.

In the present embodiment, both a limited amount of operation (the limited amount of operation for the first operation mode) Mr in the first operation mode and a limited amount of operation (the limited amount of operation for the second operation mode) Mr in the second operation mode are determined in advance and are stored in the storage unit 264 (not illustrated in FIG. 25) of the work machine controller 26. When controlling the excavator 100 in the first operation mode, the work machine controller 26 performs arm speed limitation control using the limited amount of operation Mr in the first operation mode. When controlling the excavator 100 in the second operation mode, the work machine controller 26 performs arm speed limitation control using the limited amount of operation Mr in the second operation mode.

FIG. 26 illustrates a relation between the time elapsed from the start time t0 in the first operation mode (P-mode) and the limited amount of operation Mr set by the limit value setting unit 262. A profile of the limited amount of operation Mr in the first operation mode is indicated by line S2. FIG. 26 also illustrates a relation between the time elapsed from the start time t0 and the amount of operation M of the arm 7 by the operating device 25. A profile of the amount of operation M is indicated by line S1. In FIG. 26, the horizontal axis is time (elapsed time) and the vertical axis is the amount of operation (M, Mr) of the arm 7 and the count value of the timer 261.

FIG. 27 illustrates a relation between the time elapsed from the start time t0 in the second operation mode (economy mode) and the limited amount of operation Mr set by the limit value setting unit 262. A profile of the limited amount of operation Mr in the second operation mode is indicated by line S3. FIG. 27 also illustrates the profile of the limited amount of operation Mr in the first operation mode by line S2. In FIG. 27, the horizontal axis is time (elapsed time) and the vertical axis is the amount of operation (Mr) of the arm 7 and the count value of the timer 261.

FIG. 28 illustrates a relation between the time elapsed from the start time t0 in the second operation mode and the amount of operation Mf of the arm 7 as an example. In FIG. 28, the horizontal axis is time (elapsed time) and the vertical axis is the amount of operation (Mf) of the arm 7 and the count value of the timer 261.

Similarly to the above-described embodiment, as indicated by the line S1 in FIG. 26, a case where the operating device 25 is operated by the operator so that the amount of operation M increases abruptly from 0 to value M3 will be considered. The amount of operation M maintains the value M3 for a certain period after reaching the value M3 and then decreases until it reaches 0. When the arm speed limitation control is not executed, the amount of operation M (Mf) has a profile indicated by the line S1 of FIG. 26. In this case, a delay in the raising intervention speed of the boom 6 in relation to the excavation operation of the arm 7 may occur.

The line S2 of FIG. 26 illustrates an example of the profile of the limited amount of operation Mr in the first operation mode. The profile (limit pattern) of the limited amount of operation Mr in the first operation mode illustrated in FIG. 26 is equal to the profile of the limited amount of operation Mr described with reference to FIG. 23. Description of the profile of the limited amount of operation Mr in the first operation mode will be omitted.

FIG. 27 illustrates an example of the profile of the limited amount of operation Mr in the second operation mode. The profile of the limited amount of operation Mr in the second operation mode is indicated by line S3. Similarly to the limited amount of operation Mr in the first operation mode, the limited amount of operation Mr in the second operation mode is an amount of operation that is determined in advance so that a following delay of the boom 6 does not occur. The limited amount of operation Mr in the second operation mode is smaller than the limited amount of operation Mr and the amount of operation M in the first operation mode.

In the first operation mode, in a predetermined period Ts where the time measurement is performed by the timer 261, the driving of the arm 7 is controlled so that the arm 7 is not operated with the amount of operation M larger than the limited amount of operation Mr indicated by the line S2.

In the second operation mode, in a predetermined period Ts where the time measurement is performed by the timer 261, the driving of the arm 7 is controlled so that the arm 7 is not operated with the amount of operation M larger than the limited amount of operation Mr indicated by the line S3.

The predetermined period Ts is a period between the time t0 and the time t1.

As illustrated in FIG. 27, the limited amount of operation Mr in the second operation mode is 0 at time t0 and increases from 0 to a value M2 u. The value M2 u is larger than 0 and is smaller than the value M2. That is, in a period near the start time t0, the limited amount of operation Mr in the second operation mode has the value MM2 u. The limited amount of operation Mr in the second operation mode maintains the value M2 u for a certain period after reaching the value MM2 u, and increases gradually and reaches the value M3 at the ending time t1. After that, the limited amount of operation Mr decreases until it reaches 0 after maintaining the value M3. In this manner, in the predetermined period Ts between the time t0 and the time t1, the limited amount of operation Mr in the second operation mode is set to be smaller than the limited amount of operation Mr and the amount of operation M in the first operation mode. The value at the time t0 which is the starting point of the limit pattern S3 illustrated in FIG. 27 is M2 u and the value at the time t1 which is the ending point of the limit pattern S2 is M3. In the period later than the time t1, the limited amount of operation Mr in the second operation mode is the same as the amount of operation M. Similarly to the first operation mode, in the second operation mode, the limited amount of operation Mr in the first half of the predetermined period Ts is smaller than the limited amount of operation Mr in the second half of the predetermined period Ts.

In the present embodiment, the arm control unit 263 compares the amount of operation M with the limited amount of operation Mr, selects the smaller amount of operation, and generates the control signal N based on the selected amount of operation Mf. In the present embodiment, in the predetermined period Ts between the time t0 and the time t1, the limited amount of operation Mr is smaller than the amount of operation M. Thus, in the predetermined period between the time t0 and the time t1, the arm control unit 263 generates the control signal N so that the arm 7 is driven based on the limited amount of operation Mr.

In the present embodiment, in the first operation mode, the arm control unit 263 outputs the control signal N to the control valve 271 so that the arm 7 is driven based on the limited amount of operation Mr for the first operation mode as indicated by the line S2 of FIG. 26. In the second operation mode, the arm control unit 263 generates the control signal N so that the arm 7 is driven based on the limited amount of operation Mr for the second operation mode indicated by the line S3 of FIG. 27.

In the period later than the time t1, the limited amount of operation Mr in the second operation mode is set to the value M3. In the period later than the time t1, the limited amount of operation Mr in the second operation mode is the same as the amount of operation M. Similarly to the above-described embodiment, the arm control unit 263 compares the amount of operation M with the limited amount of operation Mr and selects the amount of operation M. In the present embodiment, at the time t1, the arm speed limitation control ends. That is, in the present embodiment, the driving (arm speed limitation control) of the arm 7 based on the limited amount of operation Mr starts at the start time t0 of the time measurement of the timer 261 and ends at the ending time t1 after the elapse of the predetermined period Ts from the start time t0. After the elapse of the predetermined period Ts from the start time t0 of the time measurement of the timer 261, the driving based on the limited amount of operation Mr is disabled.

FIG. 28 illustrates an example of the profile of the amount of operation Mf in the second operation mode. The profile of the amount of operation Mf in the second operation mode is indicated by the line Sc. As illustrated in FIG. 28, in the predetermined period Ts between the time t0 and the time t1, the arm 7 is operated with the pilot pressure adjusted according to the limited amount of operation Mr for the second operation mode as indicated by the line Sc. After the elapse of the predetermined period Ts, the arm 7 is operated with the pilot pressure adjusted according to the amount of operation M as indicated by the line Sc.

That is, in the present embodiment, the profile of the amount of operation Mf of the arm 7 is determined so as to change along the line Sc of FIG. 28. Specifically, the operation of the operating device 25 starts at the time t0, and the amount of operation Mf increases abruptly from 0 to the value M2 u and maintains the value M2 u for a certain period. After that, the amount of operation Mf increases gradually and reaches the value M3 at the time t1. The amount of operation Mf maintains the value M3 for a certain period after the time t1 and then decreases to 0.

The arm control unit 263 generates the control signal N so that the arm 7 is driven with the limited amount of operation Mr for the second operation mode in the predetermined period Ts from the start time t0 of the time measurement of the timer 261.

The arm control unit 263 generates the control signal N so that the arm 7 is driven with the limited amount of operation Mr for the second operation mode in the predetermined period Ts and stops generating the control signal N so that the arm 7 is driven with the amount of operation M after the elapse of the predetermined period Ts where the driving based on the limited amount of operation Mr for the second operation mode is disabled. In this way, in the present embodiment, the arm 7 moves at a low speed in the predetermined period Ts and the arm 7 moves at a high speed after the elapse of the predetermined period Ts.

[Effects]

As described above, in the present embodiment, the limited amount of operation Mr in the second operation mode is smaller than the limited amount of operation Mr in the first operation mode.

The second operation mode is advantageous over the first operation mode in terms of fuel efficiency. On the other hand, in the second operation mode, the amount of operating oil supplied to the hydraulic cylinder 60 decreases. Thus, in the second operation mode, it is more difficult for the boom 6 and the arm 7 to move at a high speed than the first operation mode. Moreover, the possibility of the occurrence of a delay in the raising intervention speed of the boom 6 increases.

In the present embodiment, the limited amount of operation Mr in the second operation mode is smaller than the limited amount of operation Mr in the first operation mode. That is, in the second operation mode, the movement of the arm 7 is limited more strictly than the first operation mode. Due to this, the occurrence of a delay in the raising intervention speed of the boom is suppressed.

Thus, a decrease in the excavation accuracy is suppressed.

Control of Arm Third Embodiment

Next, a third embodiment of the control of the arm 7 (or the bucket 8) will be described. In the following description, the same or equivalent portions as those of the above-described embodiments will be denoted by the same reference numerals, and description thereof will be simplified or omitted.

In the present embodiment illustrated in FIG. 25, the bucket 8 is replaceable. Various buckets 8 are connected to the distal end of the arm 7.

In a state where the bucket 8 of a first weight is connected to the distal end of the arm 7, such a limit pattern indicated by the line S3 as described with reference to FIG. 27, for example, is set. Specifically, when the type of a bucket is selected, the display controller 26 transmits the selected type to the work machine controller 26. The work machine controller 26 selects a limit pattern corresponding to the type of the bucket. In a state where the bucket 8 of a second weight smaller than the first weight is connected to the distal end of the arm 7, such a limit pattern indicated by the line S2 as described with reference to FIG. 26 is set.

That is, the limited amount of operation Mr when the bucket 8 of the first weight is connected to the boom 6 with the arm 7 interposed is smaller than the limited amount of operation Mr when the bucket 8 of the second weight smaller than the first weight is connected to the boom 6 with the arm 7 interposed.

When a heavy bucket 8 is connected to the boom 6 with the arm 7 interposed, the possibility of the occurrence of a following delay of the boom 6 increases. On the other hand, if the movement of the arm 7 is limited excessively when a light bucket 8 is connected to the boom 6 with the arm 7 interposed, the workability decreases.

[Effects]

As described above, in the present embodiment, the limited amount of operation Mr when the bucket 8 of the first weight is connected is smaller than the limited amount of operation Mr when the bucket 8 of the second weight is connected. Due to this, it is possible to suppress the occurrence of a following delay of the boom 6 while suppressing a decrease in the workability.

Control of Arm Fourth Embodiment

Next, a fourth embodiment of the control of the arm 7 (or the bucket 8) will be described. In the following description, the same or equivalent portions as those of the above-described embodiments will be denoted by the same reference numerals, and description thereof will be simplified or omitted.

In the present embodiment, an example in which an amount of increase per unit time of the detection value of the detection device 70 exceeds an allowable value during the operation of the operating device 25 will be described.

FIG. 29 is a diagram illustrating an example of the amount of operation M and the limited amount of operation Mr. Similarly to the above-described embodiment, the amount of operation M of the operating device 25 is derived from the detection result of the detection device 70 (the pressure sensor 661). The amount of operation M derived from the detection result of the detection device 70 is compared with the limited amount of operation Mr (limit pattern) stored in the storage unit 264. When the amount of operation M is smaller than the limited amount of operation Mr, the arm 7 is operated based on the amount of operation M of the operating device 25.

In a state where the operating device 25 is operated so that the amount of operation M does not exceed the limited amount of operation Mr, as illustrated in FIG. 29, the operating device 25 may be operated abruptly so that the amount of operation M increases abruptly to exceed the limited amount of operation Mr. In this case, even when the amount of operation M is compared with the limited amount of operation Mr and the speed of the arm 7 is limited based on the limited amount of operation Mr, the speed of the arm 7 may not be limited sufficiently.

Thus, in the present embodiment, when the amount of operation M increases abruptly during the operation of the operating device 25, the work machine controller 26 starts (restarts) the time measurement of the timer 261 and changes a portion of the limited amount of operation Mr to perform the arm speed limitation control.

In the present embodiment, the fact that the amount of operation M increases abruptly includes the fact that the amount of increase per unit time of the amount of operation M exceeds an allowable value. In the present embodiment, the amount of operation M is derived from the detection result of the detection device 70. The fact that the amount of operation M increases abruptly includes the fact that the amount of increase per unit time of the detection value of the detection device 70 (the pressure sensor 661) exceeds an allowable value.

In the present embodiment, when the amount of increase per unit time of the detection value of the detection device 70 exceeds the allowable value, the work machine controller 26 restarts the time measurement of the timer 261 and changes a portion of the limited amount of operation Mr to perform the arm speed limitation control.

In the present embodiment, the amount of increase of the detection value of the detection device 70 (the pressure sensor 661) is a difference (deviation) between the amount of operation M of the operating device 25 detected by the detection device 70 and a processing amount R generated from the amount of operation M by a low-pass filtering process.

FIG. 30 is a diagram illustrating an example of the control system 200 according to the present embodiment. As illustrated in FIG. 30, a detection value (the amount of operation M of the operating device 25) of the detection device 70 is output to the work machine controller 26. Moreover, the detection value of the detection device 70 is output to a filtering device 71. The filtering device 71 can execute a first-order low-pass filtering process. The filtering device 71 performs a first-order low-pass filtering process on the detection value of the detection device 70 and generates a processing amount R. The work machine controller 26 calculates a deviation between the amount of operation M and the processing amount R.

FIG. 31 is a schematic view illustrating a relation between the amount of operation M and the processing amount R when the operating device 25 is operated abruptly (at a high speed). As illustrated in FIG. 31, when the operating device 25 is operated abruptly and the amount of operation M increases in a stepwise manner, the deviation between the amount of operation M and the processing amount R is large.

FIG. 32 is a schematic view illustrating a relation between the amount of operation M and the processing amount R when the operating device 25 is operated smoothly (at a low speed). As illustrated in FIG. 32, when the operating device 25 is operated smoothly and the amount of operation M increases smoothly, the deviation between the amount of operation M and the processing amount R is small.

In the present embodiment, when the operating device 25 is operated in order to drive the arm 7 to perform an excavation operation and a deviation between the amount of operation M and the processing amount R exceeds an allowable value during the operation of the operating device 25, the time measurement of the timer 261 starts (restarts).

FIG. 33 is a flowchart illustrating an example of the operation of the control system 200 according to the present embodiment. FIGS. 34, 35, and 36 are timing charts for describing an example of the operation of the control system 200 according to the present embodiment. In FIGS. 34, 35, and 36, the horizontal axis is time and the vertical axis is the amount of operation (M, Mr, and Mf) of the arm 7 and the count value of the timer.

Similarly to the above-described embodiment, when the operating device 25 starts operating the arm 7, the time measurement of the timer 261 starts (step SC1). When the arm 7 is lowered in order for the bucket 8 to perform an excavation operation, boom intervention control including the raising operation of the boom 6 is executed according to the distance d between the target designed landform U and the cutting edge 8 a (step SC2).

The amount of operation M of the operating device 25 for driving the arm 7 is detected by the detection device 70 (the pressure sensor 661) (step SC3).

Similarly to the above-described embodiment, the detection result of the amount of operation M is output to the comparing unit of the arm control unit 263. Moreover, information on the limited amount of operation Mr is output from the limit value setting unit 262 to the comparing unit of the arm control unit 263. The arm control unit 263 compares the amount of operation M with the limited amount of operation Mr according to the above-described embodiment (step SC4).

When it is determined in step SC4 that the amount of operation M is larger than the limited amount of operation Mr (that is, Yes in step SC4), the arm control unit 263 selects the limited amount of operation Mr and uses the same as the amount of operation Mf. The arm control unit 263 generates the control signal N based on the selected limited amount of operation Mr. In this way, the arm speed limitation control is performed based on the limited amount of operation Mr (step SC5).

When it is determined in step SC4 that the amount of operation M is equal to or smaller than the limited amount of operation Mr (that is, No in step SC4), the arm control unit 263 selects the amount of operation M and uses the same as the amount of operation Mf. The arm control unit 263 does not generate the control signal N. The arm 7 is driven with the pilot pressure adjusted based on the amount of operation M of the operating device 25 (step SC6).

FIG. 34 illustrates an example of the profile of the amount of operation M according to the present embodiment. The profile of the amount of operation M is indicated by line S1. As illustrated in FIG. 34, at time t0, the operating device 25 is operated by the operator in order to drive the arm 7. The timer 261 starts time measurement. In the present embodiment, as an example, as indicated by the line S1 of FIG. 34, a case where the operating device 25 is operated by the operator so that the amount of operation M increases from 0 to value M1 u will be considered.

The value M1 u is smaller than a lower limit value M1 of the amount of operation generated by the limited amount of operation Mr and the value M2 of the limited amount of operation Mr. The amount of operation M maintains the value M1 u for a certain period after reaching the value M1 u. In the present embodiment, in a period between time t0 and time t0 n, the amount of operation M maintains the value M1 u.

In FIG. 34, the profile of the limited amount of operation Mr is indicated by line S2. The limited amount of operation Mr indicated by the line S2 is the same as the limited amount of operation Mr described with reference to FIG. 23 or the like. Detailed description of the limited amount of operation Mr indicated by the line S2 will not be provided.

At the time t0, the limited amount of operation Mr indicated by the line S2 has the value M2. In the period between the time t0 and the time t0 n, the limited amount of operation Mr is equal to or larger than the value M2. That is, in the example illustrated in FIG. 34, in the period between the time t0 and the time t0 n, the amount of operation M does not exceed the limited amount of operation Mr indicated by the line S2. Thus, the arm 7 is driven based on the amount of operation M of the operating device 25.

In a state where the operating device 25 is operated so that the amount of operation M does not exceed the limited amount of operation Mr indicated by the line S2 and the arm 7 is driven based on the amount of operation M, the operating device 25 may be operated abruptly so that the amount of operation M increases abruptly as indicated by the line S1 of FIG. 34 to exceed the limited amount of operation Mr indicated by the line S2.

In the present embodiment, as illustrated in FIG. 34, at the time t0 n during the operation of the operating device 25, the operating device 25 is operated abruptly and the amount of operation M increases abruptly. As illustrated in FIG. 34, in the present embodiment, at the time t0 n, the amount of operation M increases abruptly from the value M1 u to the value M3 v. The value M3 v is larger than the value M3.

As described above, in the present embodiment, the amount of increase of the detection value of the detection device 70 (the pressure sensor 661) is a difference (deviation) between the amount of operation M of the operating device 25 detected by the detection device 70 and the processing amount R generated from the amount of operation M by a low-pass filtering process. When the amount of operation M increases abruptly, a change in the amount of operation M is detected by the detection device 70 (step SC7). The detection result of the detection device 70 is output to a determining unit of the work machine controller 26. The determining unit of the work machine controller 26 determines whether a deviation between the amount of operation M and the processing amount R exceeds an allowable value (step SC8).

When it is determined in step SC8 that the deviation is equal to or smaller than the allowable value (that is, No in step SC8), the flow returns to step SC4 and the work machine controller 26 compares the increased amount of operation M with the limited amount of operation Mr and executes the above-described process.

When it is determined in step SC8 that the deviation exceeds the allowable value (that is, Yes in step SC8), the work machine controller 26 resets the time measurement from the time t0 and starts (restarts) the time measurement of the timer 261 (step SC9).

Moreover, the limit value setting unit 262 resets the time measurement, resets the limited amount of operation Mr indicated by the line S2, and sets (resets) the limited amount of operation Mr in association with the time elapsed from the start time t0 n of the time measurement of the timer 261.

FIG. 35 illustrates an example of the profile of the reset limited amount of operation Mr. The profile of the reset limited amount of operation Mr is indicated by line S4. The limited amount of operation Mr is an amount of operation that is determined in advance so that the following delay of the boom 6 does not occur. The limited amount of operation Mr is smaller than the amount of operation M indicated by the line S1 of FIG. 34.

The time measurement of the timer 261 restarts at the time t0 n, the driving of the arm 7 is controlled so that the arm 7 is not operated with the amount of operation M larger than the limited amount of operation Mr in a predetermined period Tu where the timer 261 performs time measurement. In the present embodiment, the predetermined period Tu is a period between the time t0 n and the time t3.

As illustrated in FIG. 35, at the time t0 n, the limited amount of operation Mr has a value M2. The value

M2 is smaller than a value M3 v. The limited amount of operation Mr set to the value M2 at the time t0 n maintains the value M2 for a certain period, and increases gradually and reaches the value M3 at the time t2. After that, the limited amount of operation Mr decreases until it reaches 0 after maintaining the value M3 until the time t3. In this manner, in the predetermined period Tu between the time t0 n and the time t3, the limited amount of operation Mr is set to be smaller than the amount of operation M. The value at the time t0 n which is the starting point of the limit pattern S4 illustrated in FIG. 35 is M2, the value immediately before the time t3 which is the ending point of the limit pattern S4 is M3, and the value at the time t3 is 0.

In this manner, in the present embodiment, the limited amount of operation Mr in the first half of the predetermined period Tu is smaller than the limited amount of operation Mr in the second half of the predetermined period Tu.

The arm control unit 263 compares the amount of operation M with the reset limited amount of operation Mr (step SC10).

When it is determined in step SC10 that the amount of operation M is equal to or smaller than the limited amount of operation Mr (that is, step SC10:No), the arm control unit 263 selects the amount of operation M and uses the same as the amount of operation Mf. The arm control unit 263 does not generate the control signal N.

The arm 7 is driven with the pilot pressure adjusted based on the amount of operation M of the operating device 25 (step SC11).

When it is determined in step SC10 that the amount of operation M is larger than the limited amount of operation Mr (that is, Yes in step SC10), the arm control unit 263 selects the reset limited amount of operation Mr indicated by the line S4 and uses the same as the amount of operation Mf. The arm control unit 263 generates the control signal N based on the selected limited amount of operation Mr. In this way, the arm speed limitation control is performed based on the limited amount of operation Mr (step SC12).

In the present embodiment, as illustrated in FIGS. 34 and 35, the amount of operation M is larger than the limited amount of operation Mr indicated by the line S4. Thus, the arm control unit 263 performs arm speed limitation control based on the limited amount of operation Mr.

FIG. 36 illustrates an example of the profile of the amount of operation Mf according to the present embodiment. The profile of the amount of operation Mf is indicated by line Sc. As illustrated in FIG. 36, in a predetermined period Ts between the time t0 and the time t10, the arm 7 is operated with the pilot pressure adjusted according to the amount of operation M as indicated by the line Sc. That is, the amount of operation Mf increases from 0 to the value M1 u at the time t0 and increases from the value M1 u to the value M2 at the time t0 n after maintaining the value M1 u until the time t0 n. After that, the amount of operation Mf maintains the value M2 for a predetermined period, increases gradually to reach the value M3 at the time t2, and maintains the value M3 until the time t3.

[Effects]

As described above, according to the present embodiment, when the amount of operation M of the operating device 25 increases abruptly during the operation of the operating device 25, the time measurement of the timer 261 is reset and restarted, and the limit pattern S4 in which the value at the starting point (time t0 n) is M2 is set (reset). Thus, the arm 7 is controlled smoothly and a decrease in the excavation accuracy is suppressed.

For example, if the movement of the arm 7 is limited based on the limit pattern S2 that is set in advance without resetting the limit pattern S4, the amount of operation (the profile Sc) may increase abruptly to the value M3 based on the limit pattern S2 ni at the time t0 n. As a result, the speed of the arm 7 may increase abruptly, the intervention speed of the boom 6 may be slower than the raising speed of the arm 7, and the excavation accuracy may decrease.

According to the present embodiment, when the operating device 25 is operated abruptly so that the amount of operation M increases abruptly during the operation of the operating device 25, the time measurement of the timer 261 is reset to restart the time measurement, and a portion of the limit pattern S2 is changed to set a new limit pattern S4. Thus, it is possible to move the arm 7 smoothly and to suppress a decrease in the excavation accuracy.

Control of Arm Fifth Embodiment

Next, a fifth embodiment of the control of the arm 7 (or the bucket 8) will be described. In the following description, the same or equivalent portions as those of the above-described embodiments will be denoted by the same reference numerals, and description thereof will be simplified or omitted.

In the present embodiment, an example in which the operating device 25 is operated so that the amount of operation M decreases in the predetermined period Ts from the start time of the time measurement of the timer 261 will be described.

FIG. 37 is a diagram illustrating an example of the amount of operation M and the limited amount of operation Mr. As described above, when the amount of operation M derived from the detection value of the detection device 70 exceeds the limited amount of operation Mr, the arm 7 is operated based on the limited amount of operation Mr. As illustrated in FIG. 37, in a period where the limited amount of operation Mr increases, the operating device 25 may be operated so that the amount of operation M decreases. When the amount of operation M is larger than the limited amount of operation Mr, even if the operating device 25 is operated so that the amount of operation M decreases, the arm 7 is driven so as to be accelerated. In this case, the operator may feel a sense of incongruity.

Thus, in the present embodiment, in the predetermined period Ts from the start time t0 of the time measurement of the timer 261, when the operating device 25 is operated so that the amount of operation M decreases, the work machine controller 26 determines that the amount of operation has decreased and maintains the limited amount of operation Mr to a certain value from the decrease start time tg. When the operating device 25 is operated so that the amount of operation M decreases, since the limited amount of operation Mr is maintained to a certain value, it is possible to suppress the sense of incongruity that the operator might feel.

FIG. 38 is a functional block diagram illustrating an example of the control system 200 according to the present embodiment. FIG. 39 is a flowchart for describing an example of the operation of the control system 200 according to the present embodiment. FIGS. 40, 41, and 42 are timing charts for describing an example of the operation of the control system 200 according to the present embodiment. In FIGS. 40, 41, and 42, the horizontal axis is time and the vertical axis is the amount of operation (M, Mr, and Mf) of the arm 7 and the count value of the timer.

As illustrated in FIG. 38, in the present embodiment, the arm control unit 263 has a comparing unit 263A. The comparing unit 263A compares the amount of operation M with the limited amount of operation Mr according to the above-described embodiment.

Similarly to the above-described embodiment, when the operating device 25 starts operating the arm 7, the time measurement of the timer 261 starts (step SD1). When the arm 7 is lowered in order for the bucket 8 to perform an excavation operation, boom intervention control including the raising operation of the boom 6 is executed according to the distance d between the target designed landform U and the cutting edge 8 a (step SD2).

The amount of operation M of the operating device 25 for driving the arm 7 is detected by the detection device 70 (the pressure sensor 661) (step SD3).

Similarly to the above-described embodiment, the detection result of the amount of operation M is output to the comparing unit 263A of the arm control unit 263. Moreover, information on the limited amount of operation Mr is output from the limit value setting unit 262 to the comparing unit 263A of the arm control unit 263. The arm control unit 263 compares the amount of operation M with the limited amount of operation Mr according to the above-described embodiment (step SD4).

When it is determined in step SD4 that the amount of operation M is larger than the limited amount of operation Mr (that is, Yes in step SD4), the arm control unit 263 selects the limited amount of operation Mr and uses the same as the amount of operation Mf. The arm control unit 263 generates the control signal N based on the selected limited amount of operation Mr. In this way, the arm speed limitation control is performed based on the limited amount of operation Mr (step SD5).

When it is determined in step SD4 that the amount of operation M is equal to or smaller than the limited amount of operation Mr (that is, No in step SD4), the arm control unit 263 selects the amount of operation M and uses the same as the amount of operation Mf. The arm control unit 263 does not generate the control signal N. The arm 7 is driven with the pilot pressure adjusted based on the amount of operation M of the operating device 25 (step SD6).

FIG. 40 illustrates an example of the profile of the amount of operation M according to the present embodiment. The profile of the amount of operation M is indicated by line S1. As illustrated in FIG. 40, at time t0, the operating device 25 is operated by the operator in order to drive the arm 7. The timer 261 starts time measurement. In the present embodiment, as an example, as indicated by the line S1 of FIG. 40, a case where the operating device 25 is operated by the operator so that the amount of operation M increases from 0 to value M3 v will be considered.

The value M3 v is larger than the lower limit value M1 of the amount of operation generated by the limited amount of operation Mr, the value M2 of the limited amount of operation, and the value M3 of the largest amount of operation. The amount of operation M maintains the value M3 v for a certain period after reaching the value M3 v. In the present embodiment, in a period between time t0 and time tg, the amount of operation M maintains the value M3 v. The time tg is the time occurring after the predetermined period Ts has elapsed from the start time t0.

In FIG. 40, the profile of the limited amount of operation Mr is indicated by line S2. The limited amount of operation Mr indicated by the line S2 is the same as the limited amount of operation Mr described with reference to FIG. 23 or the like. Detailed description of the limited amount of operation Mr indicated by the line S2 will not be provided.

At the time t0, the limited amount of operation Mr indicated by the line S2 has the value M2. In the period between the time t0 and the time ta, the limited amount of operation Mr is smaller than the value M3 v of the amount of operation M. That is, in the example illustrated in FIG. 40, in the period between the time t0 and the time ta, the amount of operation M exceeds the limited amount of operation Mr indicated by the line S2. Thus, the arm 7 is driven based on the limited amount of operation Mr.

At the time tg in the predetermined period Ts, the operating device 25 is operated so that the amount of operation M decreases. That is, in a state where the arm 7 is driven based on the limited amount of operation Mr, the operating device 25 may be operated abruptly so that the amount of operation M decreases abruptly at the time tg as indicated by the line S1 of FIG. 40 and becomes smaller than the limited amount of operation Mr indicated by the line S2 at the time ta.

In the present embodiment, as illustrated in FIG. 40, at the time tg, the operating device 25 is operated abruptly and the amount of operation M decreases abruptly. As illustrated in FIG. 40, in the present embodiment, the amount of operation M decreases abruptly from the value M3 v to the value M1 v. The value M1 v of the amount of operation M is larger than the value M1 and is smaller than the value M2 of the limited amount of operation Mr.

When the amount of operation M decreases (falls) abruptly, the change in the amount of operation M is detected by the detection device 70 (step SD7). The detection result of the detection device 70 is output to a determining unit 262A of the limit value setting unit 262. The determining unit 262A determines whether a decrease rate (the amount of decrease per unit time) of the amount of operation M exceeds an allowable value (step SD8).

When it is determined in step SD8 that the decrease rate is equal to or smaller than the allowable value (that is, No in step SD8), the flow returns to step SD4 and the work machine controller 26 compares the decreased amount of operation M with the limited amount of operation Mr and executes the above-described process.

When it is determined in step SD8 that the decrease rate of the amount of operation M exceeds the allowable value (that is, Yes in step SD8), the limit value setting unit 262 of the work machine controller 26 maintains the limited amount of operation Mr at the decrease start time tg to a certain value M4 (step SD9). The limited amount of operation Mr is maintained to the value M4 from the time tg as indicated by line S2 a of FIG. 40. The arm 7 is driven based on the changed limit pattern S2 a. In this way, it is possible to suppress the sense of incongruity that the operator might feel.

When the operating device 25 is operated so that the amount of operation M decreases, the amount of operation M becomes smaller than the limited amount of operation Mr (the value M4). The arm control unit 263 compares the amount of operation M with the reset limited amount of operation Mr indicated by the line S2 a (step SD10).

When it is determined in step SD10 that the amount of operation M is equal to or smaller than the limited amount of operation Mr (that is, No in step SD10), the arm control unit 263 selects the amount of operation M and uses the same as the amount of operation Mf. The arm control unit 263 does not generate the control signal N. The arm 7 is driven with the pilot pressure adjusted based on the amount of operation M of the operating device 25 (step SD11).

When it is determined in step SD10 that the amount of operation M is larger than the limited amount of operation Mr (that is, Yes in step SD10), the arm control unit 263 selects the limited amount of operation Mr and uses the same as the amount of operation Mf. The arm control unit 263 generates the control signal N based on the selected limited amount of operation Mr. In this way, the arm speed limitation control is performed based on the limited amount of operation Mr (step SD12).

The amount of operation M indicated by the line S1 of FIG. 40 increases abruptly at time tb. When the amount of operation M increases abruptly, the time measurement of the timer 261 restarts and the limit pattern S4 a is reset according to the embodiment described with reference to FIGS. 29 to 36. FIG. 41 illustrates an example of the reset limit pattern S4 a.

FIG. 42 illustrates an example of the profile of the amount of operation Mf according to the present embodiment. The profile of the amount of operation Mf is indicated by line Sc. As illustrated in FIG. 42, in the period Ts between the time t0 and the time ta, the arm 7 is operated with the pilot pressure adjusted according to the limited amount of operation Mr as indicated by the line Sc. In the period later than the time ta, the arm 7 is operated with the pilot pressure adjusted according to the amount of operation M. In the period later than the time tb, the arm 7 is operated with the pilot pressure adjusted according to the limited amount of operation Mr.

[Effects]

As described above, according to the present embodiment, when the arm 7 is driven based on the limit pattern S2, the arm 7 is moved so as to be accelerated, and the operating device 25 is operated so as to be decelerated, a portion of the limit pattern S2 is changed to obtain the limit pattern S2 a so that the limited amount of operation Mr is maintained to a certain value without being increased. Thus, it is possible to suppress the sense of incongruity that the operator might feel.

Control of Arm Sixth Embodiment

Next, a sixth embodiment of the control of the arm 7 (or the bucket 8) will be described. In the following description, the same or equivalent portions as those of the above-described embodiments will be denoted by the same reference numerals, and description thereof will be simplified or omitted.

FIG. 43 is a functional block diagram of the control system 200 according to the present embodiment. As illustrated in FIG. 43, in the present embodiment, the work machine controller 26 has a distance determining unit 262B.

FIG. 44 is a schematic view illustrating an example of the excavator 100 according to the present embodiment. As illustrated in FIG. 44, the excavator 100 includes the vehicle body 1 and the work machine 2. The vehicle body 1 supports the boom 6. When the work machine 2 is driven, the distance x between the reference position P2 of the vehicle body 1 and the position P3 of the cutting edge 8 a of the bucket 8 changes. The distance x may be the distance between the position of the boom pin and the position of the cutting edge 8 a and may be the distance between the installed position P1 and the cutting edge 8 a.

In the present embodiment, the distance x between the reference position P2 and the position P3 is calculated from the tilt angles θ1 to θ3 of the work machines output from the sensor controller 30, and the limited amount of operation Mr when the work machine 2 is driven so that the distance x between the reference position P2 and the position P3 is a first distance is smaller than the limited amount of operation Mr when the work machine 2 is driven so that the distance x between the reference position P2 and the position P3 is a second distance shorter than the first distance.

FIG. 45 is a timing chart for describing an example of the operation of the control system 200 according to the present embodiment. In FIG. 45, the horizontal axis is time and the vertical axis is the amount of operation M (limited amount of operation Mr) of the arm 7 and the count value of the timer.

As illustrated in FIG. 45, when the distance x is a first distance, such a limit pattern as indicated by the line S2 is set. When the distance x is a second distance, such a limit pattern as indicated by the line S5 is set. The limited amount of operation Mr of the limit pattern indicated by the line S2 is smaller than the limited amount of operation Mr of the limit pattern indicated by the line S5.

FIG. 46 illustrates an example of the profile of the amount of operation Mf determined based on the limit pattern S2. FIG. 47 illustrates an example of the profile of the amount of operation Mf determined based on the limit pattern S5.

The longer the distance x, the larger the moment of the work machine 2, and the higher the possibility of the occurrence of a following delay of the boom 6. In the present embodiment, the limited amount of operation Mr when the distance x is the first distance which is long is smaller than the limited amount of operation Mr when the distance x is the second distance which is short. That is, in the first distance state, the movement of the arm 7 is limited more strictly than in the second distance state. In this way, the occurrence of the following delay of the boom 6 is suppressed. Thus, a decrease in the excavation accuracy is suppressed.

[Effects]

As described above, according to the present embodiment, the limited amount of operation Mr when the work machine 2 is driven so that the distance between the reference position of the vehicle body 1 and the bucket 8 is the first distance is smaller than the limited amount of operation Mr when the work machine 2 is driven so that the distance between the reference position of the vehicle body 1 and the bucket 8 is the second distance shorter than the first distance. Thus, it is possible to suppress a decrease in the excavation accuracy while suppressing a decrease in the operation efficiency.

While the embodiments of the present invention have been described, the present invention is not limited to the embodiments and various changes can be made without departing from the spirit of the present invention.

For example, in the above-described embodiments, the operating device 25 is a pilot hydraulic-type operating device. The operating device 25 may be an electric lever-type operating device. For example, an operating lever detecting unit that detects an amount of operation of the operating lever of the operating device 25 with the aid of a potentiometer or the like and outputs a detection value corresponding to the amount of operation to the work machine controller 26 may be provided. The work machine controller 26 may output a control signal to the direction control valve 64 based on the detection result of the operating lever detecting unit to adjust the amount of operating oil supplied to the hydraulic cylinder. The control according to the present invention may be performed by other controllers such as the sensor controller 30 as well as a work machine controller 226.

In the above-described embodiments, although an excavator has been described as an example of the construction machine, the construction machine is not limited to the excavator, and the present invention may be applied to other types of construction machine.

The position of the excavator CM in the global coordinate system may be acquired by other position measurement means without being limited to GNSS. Thus, the distance d between the designed landform and the cutting edge 8 a may be acquired by other position measurement means without being limited to GNSS.

REFERENCE SIGNS LIST

1 VEHICLE BODY

2 WORK MACHINE

3 REVOLVING STRUCTURE

4 CAB

5 TRAVELING DEVICE

5Cr CRAWLER BELT

6 BOOM

7 ARM

8 BUCKET

9 ENGINE ROOM

10 BOOM CYLINDER

11 ARM CYLINDER

12 BUCKET CYLINDER

13 BOOM PIN

14 ARM PIN

15 BUCKET PIN

16 FIRST CYLINDER STROKE SENSOR

17 SECOND CYLINDER STROKE SENSOR

18 THIRD CYLINDER STROKE SENSOR

19 HANDRAIL

20 POSITION DETECTION DEVICE

21 ANTENNA

23 GLOBAL COORDINATE CALCULATING UNIT

24 IMU

25 OPERATING DEVICE

25L SECOND OPERATING LEVER

25R FIRST OPERATING LEVER

26 WORK MACHINE CONTROLLER

27 CONTROL VALVE

28 DISPLAY CONTROLLER

29 DISPLAY UNIT

31 BOOM OPERATION OUTPUT UNIT

32 BUCKET OPERATION OUTPUT UNIT

33 ARM OPERATION OUTPUT UNIT

34 REVOLVING OPERATION OUTPUT UNIT

40A CAB-SIDE OIL CHAMBER

40B ROD-SIDE OIL CHAMBER

41 HYDRAULIC PUMP

41A SWASH PLATE

45 DISCHARGE OIL PASSAGE

47 OIL PASSAGE

48 OIL PASSAGE

49 PUMP CONTROLLER

50 OIL PASSAGE

51 SHUTTLE VALVE

60 HYDRAULIC CYLINDER

63 REVOLVING MOTOR

64 DIRECTION CONTROL VALVE

65 SPOOL STROKE SENSOR

66 PRESSURE SENSOR

67 PRESSURE SENSOR

70 DETECTION DEVICE

71 FILTERING DEVICE

100 CONSTRUCTION MACHINE (EXCAVATOR)

161 ROTATION ROLLER

162 ROTATION CENTER SHAFT

163 ROTATION SENSOR PORTION

164 CASE

200 CONTROL SYSTEM

300 HYDRAULIC SYSTEM

AX REVOLUTION AXIS

Q REVOLVING STRUCTURE DIRECTION DATA

S CUTTING EDGE POSITION DATA

T TARGET CONSTRUCTION INFORMATION

U TARGET EXCAVATION LANDFORM 

1. A construction machine control system that includes a work machine including a boom, an arm, and a bucket, the system comprising: a boom limiting unit that determines a speed limit according to a distance between the bucket and a target excavation landform indicating a target shape of an excavation object based on the target excavation landform and bucket position data indicating the position of the bucket and limits the speed of the boom so that a speed at which the work machine approaches the target excavation landform is equal to or smaller than the speed limit; an operating device that is operated in order to drive a movable member including at least one of the arm and the bucket; a detection device that detects an amount of operation of the operating device; and a movable member control unit that outputs a control signal so that the movable member is driven with a limited amount of operation for limiting a speed of the movable member based on a detection result of the detection device.
 2. The construction machine control system according to claim 1, further comprising: a timer that starts time measurement based on the detection result of the detection device; and a limit value setting unit that sets the limited amount of operation for limiting the speed of the movable member in association with time elapsed from a start time of the time measurement of the timer, wherein the movable member control unit outputs a control signal so that the movable member is driven with the limited amount of operation in a predetermined period from the start time of the time measurement of the timer.
 3. The construction machine control system according to claim 2, wherein the start time of the time measurement of the timer includes at least one of a start time of an operation of the operating device, time at which a detection value of the detection device exceeds a threshold value, and time at which an amount of increase per unit time of the detection value of the detection device exceeds an allowable value.
 4. The construction machine control system according to claim 2, wherein the driving based on the limited amount of operation is disabled when the predetermined period has elapsed from the start time of the time measurement.
 5. The construction machine control system according to claim 2, wherein the limited amount of operation in a first half of the predetermined period is smaller than the limited amount of operation in a second half.
 6. The construction machine control system according to claim 1, further comprising: a hydraulic system that includes a first hydraulic actuator for driving the boom and a second hydraulic actuator for driving the movable member, wherein in an excavation operation of the bucket, the hydraulic system is operated so that the boom is raised and the arm is lowered, and the hydraulic system is driven with the limited amount of operation when the arm is lowered.
 7. The construction machine control system according to claim 6, wherein the hydraulic system includes a control valve that adjusts an amount of operating oil supplied to the second hydraulic actuator, and the control signal is output to the control valve.
 8. The construction machine control system according to claim 6, wherein the hydraulic system includes: a hydraulic pump that supplies operating oil; and a pump control unit that controls the hydraulic pump so that the operating oil is supplied with a first largest discharge capacity from the hydraulic pump in a first operation mode and the operating oil is supplied with a second largest discharge capacity smaller than the first largest discharge capacity from the hydraulic pump in a second operation mode, and the limited amount of operation in the second operation mode is smaller than the limited amount of operation in the first operation mode.
 9. The construction machine control system according to claim 1, wherein the movable member is replaceable, and the limited amount of operation when the movable member of a first weight is connected to the boom is smaller than the limited amount of operation when the movable member of a second weight smaller than the first weight is connected.
 10. The construction machine control system according to claim 1, wherein the output of the control signal is started so that the movable member is driven with the limited amount of operation when an amount of increase per unit time of the detection value of the detection device exceeds an allowable value, and the amount of increase includes a difference between the amount of operation of the operating device and a processing amount generated by low-pass filtering of the amount of operation.
 11. The construction machine control system according to claim 1, wherein when the operating device is operated so that the amount of operation decreases, the limited amount of operation is maintained to a certain value from a decrease start time.
 12. The construction machine control system according to claim 11, wherein the movable member is driven based on the amount of operation when the amount of operation is smaller than the limited amount of operation.
 13. The construction machine control system according to claim 1, wherein the construction machine includes a vehicle body that supports the boom, and the limited amount of operation when the work machine is driven so that a distance between the bucket and a reference position of the vehicle body is a first distance is smaller than the limited amount of operation when the work machine is driven so that the distance between the bucket and the reference position is a second distance shorter than the first distance.
 14. A construction machine comprising: a lower traveling structure; an upper revolving structure that is supported by the lower traveling structure; a work machine that includes a boom, an arm and a bucket and is supported by the upper revolving structure; and the control system according to claim
 1. 15. A method of controlling a construction machine that includes a work machine including a boom, an arm, and a bucket, the method comprising: determining a speed limit according to a distance between the bucket and a target excavation landform indicating a target shape of an excavation object based on the target excavation landform and bucket position data indicating a position of the bucket and limiting a speed of the boom so that a speed at which the work machine approaches the target excavation landform is equal to or smaller than the speed limit; operating an operating device in order to drive a movable member including at least one of the arm and the bucket; detecting an amount of operation of the operating device; setting a limited amount of operation for limiting a speed of the movable member based on a detection result of the detection device; and outputting a control signal so that the movable member is driven with the limited amount of operation. 